fix(ngRepeat): improve errors for duplicate items

-Log the value that had the duplicate key, as well as the key
The error that is thrown when items have duplicate track by keys can be
confusing because only the duplicate key is logged.  If the user didn't
provide that key themselves, they may not know what it is or what item
it corresponds to.

Author: smilli

src/ng/directive/ngRepeat.js

@@ -309,8 +309,9 @@ var ngRepeatDirective = ['$parse', '$animate', function($parse, $animate) {
                if (block && block.scope) lastBlockMap[block.id] = block;
              });
              // This is a duplicate and we need to throw an error
-             throw ngRepeatMinErr('dupes', "Duplicates in a repeater are not allowed. Use 'track by' expression to specify unique keys. Repeater: {0}, Duplicate key: {1}",
-                                                                                                                                                    expression,       trackById);
+             throw ngRepeatMinErr('dupes',
+                  "Duplicates in a repeater are not allowed. Use 'track by' expression to specify unique keys. Repeater: {0}, Duplicate key: {1}, Duplicate value: {2}",
+                  expression, trackById, toJson(value));
            } else {
              // new never before seen block
              nextBlockOrder[index] = { id: trackById };

test/ng/directive/ngRepeatSpec.js

@@ -940,7 +940,8 @@ describe('ngRepeat', function() {
       scope.items = [a, a, a];
       scope.$digest();
       expect($exceptionHandler.errors.shift().message).
-          toMatch(/^\[ngRepeat:dupes\] Duplicates in a repeater are not allowed\. Use 'track by' expression to specify unique keys\. Repeater: item in items, Duplicate key: object:003/);
+          toMatch(
+            /^\[ngRepeat:dupes\] Duplicates in a repeater are not allowed\. Use 'track by' expression to specify unique keys\. Repeater: item in items, Duplicate key: object:003, Duplicate value: {}/);
 
       // recover
       scope.items = [a];
@@ -960,7 +961,8 @@ describe('ngRepeat', function() {
       scope.items = [d, d, d];
       scope.$digest();
       expect($exceptionHandler.errors.shift().message).
-          toMatch(/^\[ngRepeat:dupes\] Duplicates in a repeater are not allowed\. Use 'track by' expression to specify unique keys\. Repeater: item in items, Duplicate key: object:009/);
+          toMatch(
+            /^\[ngRepeat:dupes\] Duplicates in a repeater are not allowed\. Use 'track by' expression to specify unique keys\. Repeater: item in items, Duplicate key: object:009, Duplicate value: {}/);
 
       // recover
       scope.items = [a];