[atoms] Cleaning up getAttribute dependencies, reducing size from 36K to 7K

The getAttribute atom had a transitive dependency on wgxpath, which was
never being flagged for dead-code removal by the Closure compiler. This
unnecessarily bloats the atom.

As a workaround, move the atom's definition from
webdriver.atoms.element.getAttribute to a new module:
webdriver.atoms.element.attribute (with a single exported "get"
function). Also moving all of the new module's bot.dom dependencies to a
new namespace, bot.dom.core. Having to rearrange the code like this is
a bit unfortunate, but I cannot figure out why the compiler is not pruning
wgxpath from the atom.

Author: jleyba

javascript/atoms/BUCK

@@ -56,12 +56,28 @@ js_library(name = 'devices',
 )
 
 
+js_library(name = 'domcore',
+  srcs = [
+    "domcore.js",
+  ],
+  deps = [
+    ':errors',
+    ':useragent',
+    '//third_party/closure:closure',
+  ],
+  visibility = [
+    '//javascript/...',
+  ],
+)
+
+
 js_library(name = 'dom',
   srcs = [
     "dom.js",
   ],
   deps = [
     ':bot',
+    ':domcore',
     ':color',
     ':json',
     ':xpath',
@@ -160,6 +176,19 @@ js_library(name = 'locators',
 )
 
 
+js_library(name = 'useragent',
+  srcs = [
+    'userAgent.js',
+  ],
+  deps = [
+    '//third_party/closure:closure',
+  ],
+  visibility = [
+    '//javascript/...',
+  ],
+)
+
+
 js_library(name = 'window',
   srcs = [
     'frame.js',

javascript/atoms/build.desc

@@ -17,6 +17,7 @@ js_library(name = "all_js",
 js_library(name = "dom",
   srcs = [
     "dom.js",
+    "domcore.js",
   ])
 
 js_library(name = "error_lib",

javascript/atoms/dom.js

@@ -23,6 +23,7 @@ goog.provide('bot.dom');
 
 goog.require('bot');
 goog.require('bot.color');
+goog.require('bot.dom.core');
 goog.require('bot.locators.xpath');
 goog.require('bot.userAgent');
 goog.require('goog.array');
@@ -66,18 +67,9 @@ bot.dom.getActiveElement = function(nodeOrWindow) {
 
 
 /**
- * Returns whether the given node is an element and, optionally, whether it has
- * the given tag name. If the tag name is not provided, returns true if the node
- * is an element, regardless of the tag name.h
- *
- * @param {Node} node The node to test.
- * @param {string=} opt_tagName Tag name to test the node for.
- * @return {boolean} Whether the node is an element with the given tag name.
+ * @const
  */
-bot.dom.isElement = function(node, opt_tagName) {
-  return !!node && node.nodeType == goog.dom.NodeType.ELEMENT &&
-      (!opt_tagName || node.tagName.toUpperCase() == opt_tagName);
-};
+bot.dom.isElement = bot.dom.core.isElement;
 
 
 /**
@@ -113,45 +105,15 @@ bot.dom.hasPointerEventsDisabled_ = function(element) {
 
 
 /**
- * Returns whether the element can be checked or selected.
- *
- * @param {!Element} element The element to check.
- * @return {boolean} Whether the element could be checked or selected.
+ * @const
  */
-bot.dom.isSelectable = function(element) {
-  if (bot.dom.isElement(element, goog.dom.TagName.OPTION)) {
-    return true;
-  }
-
-  if (bot.dom.isElement(element, goog.dom.TagName.INPUT)) {
-    var type = element.type.toLowerCase();
-    return type == 'checkbox' || type == 'radio';
-  }
-
-  return false;
-};
+bot.dom.isSelectable = bot.dom.core.isSelectable;
 
 
 /**
- * Returns whether the element is checked or selected.
- *
- * @param {!Element} element The element to check.
- * @return {boolean} Whether the element is checked or selected.
+ * @const
  */
-bot.dom.isSelected = function(element) {
-  if (!bot.dom.isSelectable(element)) {
-    throw new bot.Error(bot.ErrorCode.ELEMENT_NOT_SELECTABLE,
-        'Element is not selectable');
-  }
-
-  var propertyName = 'selected';
-  var type = element.type && element.type.toLowerCase();
-  if ('checkbox' == type || 'radio' == type) {
-    propertyName = 'checked';
-  }
-
-  return !!bot.dom.getProperty(element, propertyName);
-};
+bot.dom.isSelected = bot.dom.core.isSelected;
 
 
 /**
@@ -190,123 +152,15 @@ bot.dom.isFocusable = function(element) {
 
 
 /**
- * Looks up the given property (not to be confused with an attribute) on the
- * given element.
- *
- * @param {!Element} element The element to use.
- * @param {string} propertyName The name of the property.
- * @return {*} The value of the property.
- */
-bot.dom.getProperty = function(element, propertyName) {
-  // When an <option>'s value attribute is not set, its value property should be
-  // its text content, but IE < 8 does not adhere to that behavior, so fix it.
-  // http://www.w3.org/TR/1999/REC-html401-19991224/interact/forms.html#adef-value-OPTION
-  if (bot.userAgent.IE_DOC_PRE8 && propertyName == 'value' &&
-      bot.dom.isElement(element, goog.dom.TagName.OPTION) &&
-      goog.isNull(bot.dom.getAttribute(element, 'value'))) {
-    return goog.dom.getRawTextContent(element);
-  }
-  return element[propertyName];
-};
-
-
-/**
- * Regex to split on semicolons, but not when enclosed in parens or quotes.
- * Helper for {@link bot.dom.standardizeStyleAttribute_}.
- * If the style attribute ends with a semicolon this will include an empty
- * string at the end of the array
- * @private {!RegExp}
  * @const
  */
-bot.dom.SPLIT_STYLE_ATTRIBUTE_ON_SEMICOLONS_REGEXP_ =
-    new RegExp('[;]+' +
-               '(?=(?:(?:[^"]*"){2})*[^"]*$)' +
-               '(?=(?:(?:[^\']*\'){2})*[^\']*$)' +
-               '(?=(?:[^()]*\\([^()]*\\))*[^()]*$)');
+bot.dom.getProperty = bot.dom.core.getProperty;
 
 
 /**
- * Standardize a style attribute value, which includes:
- *  (1) converting all property names lowercase
- *  (2) ensuring it ends in a trailing semi-colon
- * @param {string} value The style attribute value.
- * @return {string} The identical value, with the formatting rules described
- *     above applied.
- * @private
- */
-bot.dom.standardizeStyleAttribute_ = function(value) {
-  var styleArray = value.split(
-      bot.dom.SPLIT_STYLE_ATTRIBUTE_ON_SEMICOLONS_REGEXP_);
-  var css = [];
-  goog.array.forEach(styleArray, function(pair) {
-    var i = pair.indexOf(':');
-    if (i > 0) {
-      var keyValue = [pair.slice(0, i), pair.slice(i + 1)];
-      if (keyValue.length == 2) {
-        css.push(keyValue[0].toLowerCase(), ':', keyValue[1], ';');
-      }
-    }
-  });
-  css = css.join('');
-  css = css.charAt(css.length - 1) == ';' ? css : css + ';';
-  return css;
-};
-
-
-/**
- * Get the user-specified value of the given attribute of the element, or null
- * if the attribute is not present.
- *
- * <p>For boolean attributes such as "selected" or "checked", this method
- * returns the value of element.getAttribute(attributeName) cast to a String
- * when attribute is present. For modern browsers, this will be the string the
- * attribute is given in the HTML, but for IE8 it will be the name of the
- * attribute, and for IE7, it will be the string "true". To test whether a
- * boolean attribute is present, test whether the return value is non-null, the
- * same as one would for non-boolean attributes. Specifically, do *not* test
- * whether the boolean evaluation of the return value is true, because the value
- * of a boolean attribute that is present will often be the empty string.
- *
- * <p>For the style attribute, it standardizes the value by lower-casing the
- * property names and always including a trailing semi-colon.
- *
- * @param {!Element} element The element to use.
- * @param {string} attributeName The name of the attribute to return.
- * @return {?string} The value of the attribute or "null" if entirely missing.
+ * @const
  */
-bot.dom.getAttribute = function(element, attributeName) {
-  attributeName = attributeName.toLowerCase();
-
-  // The style attribute should be a css text string that includes only what
-  // the HTML element specifies itself (excluding what is inherited from parent
-  // elements or style sheets). We standardize the format of this string via the
-  // standardizeStyleAttribute method.
-  if (attributeName == 'style') {
-    return bot.dom.standardizeStyleAttribute_(element.style.cssText);
-  }
-
-  // In IE doc mode < 8, the "value" attribute of an <input> is only accessible
-  // as a property.
-  if (bot.userAgent.IE_DOC_PRE8 && attributeName == 'value' &&
-      bot.dom.isElement(element, goog.dom.TagName.INPUT)) {
-    return element['value'];
-  }
-
-  // In IE < 9, element.getAttributeNode will return null for some boolean
-  // attributes that are present, such as the selected attribute on <option>
-  // elements. This if-statement is sufficient if these cases are restricted
-  // to boolean attributes whose reflected property names are all lowercase
-  // (as attributeName is by this point), like "selected". We have not
-  // found a boolean attribute for which this does not work.
-  if (bot.userAgent.IE_DOC_PRE9 && element[attributeName] === true) {
-    return String(element.getAttribute(attributeName));
-  }
-
-  // When the attribute is not present, either attr will be null or
-  // attr.specified will be false.
-  var attr = element.getAttributeNode(attributeName);
-  return (attr && attr.specified) ? attr.value : null;
-};
+bot.dom.getAttribute = bot.dom.core.getAttribute;
 
 
 /**