feat(ngRepeat): New exposed properties

Added new exposed properties to ngRepeat:
-  string to identify the key (if applicable)
-  string to identify the variable

This allows you to access the key/var from scope inside a directive without
needing to know the exact name it was given.

Author: marcfallows

src/ng/directive/ngRepeat.js

@@ -15,6 +15,8 @@
  *   * `$first` – `{boolean}` – true if the repeated element is first in the iterator.
  *   * `$middle` – `{boolean}` – true if the repeated element is between the first and last in the iterator.
  *   * `$last` – `{boolean}` – true if the repeated element is last in the iterator.
+ *   * `$keyIdentifier` – `{string}` – Identifier for the key in the (key,value) pair in the expression (if applicable)
+ *   * `$varIdentifier` – `{string}` – Identifier for the variable in the expression
  *
  *
  * @element ANY
@@ -151,6 +153,8 @@ var ngRepeatDirective = ngDirective({
           childScope.$first = (index === 0);
           childScope.$last = (index === (collectionLength - 1));
           childScope.$middle = !(childScope.$first || childScope.$last);
+          childScope.$varIdentifier = valueIdent;
+          if (keyIdent) childScope.$keyIdentifier = keyIdent;
 
           if (!last) {
             linker(childScope, function(clone){

test/ng/directive/ngRepeatSpec.js

@@ -215,6 +215,29 @@ describe('ngRepeat', function() {
   });
 
 
+  it('should expose identifier as $varIdentifier when iterating over arrays',
+      function() {
+    element = $compile(
+      '<ul>' +
+        '<li ng-repeat="item in items">{{item}}:{{$varIdentifier}}:{{$keyIdentifier}}|</li>' +
+      '</ul>')(scope);
+    scope.items = ['misko', 'shyam', 'frodo'];
+    scope.$digest();
+    expect(element.text()).toEqual('misko:item:|shyam:item:|frodo:item:|');
+  });
+
+
+  it('should expose identifiers as $keyIdentifier, $varIdentifier when iterating over objects', function() {
+    element = $compile(
+      '<ul>' +
+        '<li ng-repeat="(key, val) in items">{{key}}:{{val}}:{{$varIdentifier}}:{{$keyIdentifier}}|</li>' +
+      '</ul>')(scope);
+    scope.items = {'misko':'m', 'shyam':'s', 'frodo':'f'};
+    scope.$digest();
+    expect(element.text()).toEqual('frodo:f:val:key|misko:m:val:key|shyam:s:val:key|');
+  });
+
+
   it('should expose iterator offset as $index when iterating over arrays',
       function() {
     element = $compile(