fix(gesture): unable to move text cursor and tap away on mobile (#10821)

* Fixes not being able to move the text cursor within and input on mobile.
* Fixes not being able to blur an input by tapping away on mobile.

Both of the issues were due to the click hijacking from the gesture service being too aggressive and preventing focus from shifting.

Fixes #10301.
Fixes #5365.

Author: crisbeto

src/core/services/gesture/gesture.js

@@ -104,20 +104,9 @@ function MdGesture($$MdGestureHandler, $$rAF, $timeout) {
         maxDistance: maxClickDistance
       },
       onEnd: function(ev, pointer) {
-        if (pointer.distance < this.state.options.maxDistance) {
-          if (canFocus(ev.target)) {
-            this.dispatchEvent(ev, 'focus', pointer);
-            ev.target.focus();
-          }
-        }
-
-        function canFocus(element) {
-          var focusableElements = ['INPUT', 'SELECT', 'BUTTON', 'TEXTAREA', 'VIDEO', 'AUDIO'];
-
-          return (element.getAttribute('tabindex') != '-1') &&
-              !element.hasAttribute('DISABLED') &&
-              (element.hasAttribute('tabindex') || element.hasAttribute('href') || element.isContentEditable ||
-              (focusableElements.indexOf(element.nodeName) != -1));
+        if (pointer.distance < this.state.options.maxDistance && canFocus(ev.target)) {
+          this.dispatchEvent(ev, 'focus', pointer);
+          ev.target.focus();
         }
       }
     });
@@ -550,8 +539,14 @@ function attachToDocument( $mdGesture, $$MdGestureHandler ) {
 
   function mouseInputHijacker(ev) {
     var isKeyClick = !ev.clientX && !ev.clientY;
-    if (!isKeyClick && !ev.$material && !ev.isIonicTap
-      && !isInputEventFromLabelClick(ev)) {
+
+    if (
+      !isKeyClick &&
+      !ev.$material &&
+      !ev.isIonicTap &&
+      !isInputEventFromLabelClick(ev) &&
+      (ev.type !== 'mousedown' || (!canFocus(ev.target) && !canFocus(document.activeElement)))
+    ) {
       ev.preventDefault();
       ev.stopPropagation();
     }
@@ -745,3 +740,18 @@ function getEventPoint(ev) {
     (ev.changedTouches && ev.changedTouches[0]) ||
     ev;
 }
+
+/** Checks whether an element can be focused. */
+function canFocus(element) {
+  return (
+    !!element &&
+    element.getAttribute('tabindex') != '-1' &&
+    !element.hasAttribute('disabled') &&
+    (
+      element.hasAttribute('tabindex') ||
+      element.hasAttribute('href') ||
+      element.isContentEditable ||
+      ['INPUT', 'SELECT', 'BUTTON', 'TEXTAREA', 'VIDEO', 'AUDIO'].indexOf(element.nodeName) != -1
+    )
+  );
+}