Move MapEntry type def to global scope.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=148802193

src/com/google/javascript/jscomp/js/es6/map.js

@@ -20,6 +20,35 @@
 'require util/owns';
 'require util/polyfill';
 
+
+/**
+ * Internal record type for entries.
+ * @record
+ * @template KEY, VALUE
+ */
+$jscomp.MapEntry = function() {};
+
+
+/** @type {!$jscomp.MapEntry<KEY, VALUE>} */
+$jscomp.MapEntry.prototype.previous;
+
+
+/** @type {!$jscomp.MapEntry<KEY, VALUE>} */
+$jscomp.MapEntry.prototype.next;
+
+
+/** @type {?Object} */
+$jscomp.MapEntry.prototype.head;
+
+
+/** @type {KEY} */
+$jscomp.MapEntry.prototype.key;
+
+
+/** @type {VALUE} */
+$jscomp.MapEntry.prototype.value;
+
+
 /**
  * Whether to skip the conformance check and simply use the polyfill always.
  * @define {boolean}
@@ -70,34 +99,6 @@ $jscomp.polyfill('Map', function(NativeMap) {
   var idMap = new WeakMap();
 
 
-  /**
-   * Internal record type for entries.
-   * @record
-   * @template KEY, VALUE
-   */
-  var MapEntry = function() {};
-
-
-  /** @type {!MapEntry<KEY, VALUE>} */
-  MapEntry.prototype.previous;
-
-
-  /** @type {!MapEntry<KEY, VALUE>} */
-  MapEntry.prototype.next;
-
-
-  /** @type {?Object} */
-  MapEntry.prototype.head;
-
-
-  /** @type {KEY} */
-  MapEntry.prototype.key;
-
-
-  /** @type {VALUE} */
-  MapEntry.prototype.value;
-
-
   /**
    * Polyfill for the global Map data type.
    * @constructor
@@ -110,10 +111,10 @@ $jscomp.polyfill('Map', function(NativeMap) {
    */
   // TODO(sdh): fix param type if heterogeneous arrays ever supported.
   var PolyfillMap = function(opt_iterable) {
-    /** @private {!Object<!Array<!MapEntry<KEY, VALUE>>>} */
+    /** @private {!Object<!Array<!$jscomp.MapEntry<KEY, VALUE>>>} */
     this.data_ = {};
 
-    /** @private {!MapEntry<KEY, VALUE>} */
+    /** @private {!$jscomp.MapEntry<KEY, VALUE>} */
     this.head_ = createHead();
 
     // Note: this property should not be changed.  If we're willing to give up
@@ -200,20 +201,28 @@ $jscomp.polyfill('Map', function(NativeMap) {
 
   /** @override */
   PolyfillMap.prototype.entries = function() {
-    return makeIterator(
-        this, function(entry) { return [entry.key, entry.value]; });
+    return makeIterator(this, /** @return {!Array<(KEY|VALUE)>} */ function(
+        /** !$jscomp.MapEntry<KEY, VALUE> */ entry) {
+      return ([entry.key, entry.value]);
+    });
   };
 
 
   /** @override */
   PolyfillMap.prototype.keys = function() {
-    return makeIterator(this, function(entry) { return entry.key; });
+    return makeIterator(this, /** @return {KEY} */ function(
+        /** !$jscomp.MapEntry<KEY, VALUE> */ entry) {
+      return entry.key;
+    });
   };
 
 
   /** @override */
   PolyfillMap.prototype.values = function() {
-    return makeIterator(this, function(entry) { return entry.value; });
+    return makeIterator(this, /** @return {VALUE} */ function(
+        /** !$jscomp.MapEntry<KEY, VALUE> */ entry) {
+      return entry.value;
+    });
   };
 
 
@@ -241,9 +250,9 @@ $jscomp.polyfill('Map', function(NativeMap) {
    * @param {!PolyfillMap<KEY, VALUE>} map
    * @param {KEY} key
    * @return {{id: string,
-   *           list: (!Array<!MapEntry<KEY, VALUE>>|undefined),
+   *           list: (!Array<!$jscomp.MapEntry<KEY, VALUE>>|undefined),
    *           index: number,
-   *           entry: (!MapEntry<KEY, VALUE>|undefined)}}
+   *           entry: (!$jscomp.MapEntry<KEY, VALUE>|undefined)}}
    * @template KEY, VALUE
    */
   var maybeGetEntry = function(map, key) {
@@ -264,7 +273,7 @@ $jscomp.polyfill('Map', function(NativeMap) {
   /**
    * Maps over the entries with the given function.
    * @param {!PolyfillMap<KEY, VALUE>} map
-   * @param {function(!MapEntry<KEY, VALUE>): T} func
+   * @param {function(!$jscomp.MapEntry<KEY, VALUE>): T} func
    * @return {!IteratorIterable<T>}
    * @template KEY, VALUE, T
    * @private
@@ -289,12 +298,12 @@ $jscomp.polyfill('Map', function(NativeMap) {
 
   /**
    * Makes a new "head" element.
-   * @return {!MapEntry<KEY, VALUE>}
+   * @return {!$jscomp.MapEntry<KEY, VALUE>}
    * @template KEY, VALUE
    * @suppress {checkTypes} ignore missing key/value for head only
    */
   var createHead = function() {
-    var head = /** type {!MapEntry<KEY, VALUE>} */ ({});
+    var head = /** type {!$jscomp.MapEntry<KEY, VALUE>} */ ({});
     head.previous = head.next = head.head = head;
     return head;
   };