fix($compile): bind ng-attr-* even if unbound attribute follows ng-attr-*

Previously, <element ng-attr-foo="{{binding}}" foo="bar"></element>'s "foo" attribute would always
equal "bar", because the bound version was overwritten. This CL corrects this behaviour and ensures
that the ordering of attributes does not have an effect on whether or not ng-attr-bound attributes
do their work.

Closes angular#7739

Author: jbedard

test/ng/compileSpec.js

@@ -5187,6 +5187,83 @@ describe('$compile', function() {
       expect(element.attr('test')).toBe('Misko');
     }));
 
+    it('should bind after digest but not before when after overridden attribute', inject(function($compile, $rootScope) {
+      $rootScope.name = "Misko";
+      element = $compile('<span test="123" ng-attr-test="{{name}}"></span>')($rootScope);
+      expect(element.attr('test')).toBe('123');
+      $rootScope.$digest();
+      expect(element.attr('test')).toBe('Misko');
+    }));
+
+    it('should bind after digest but not before when before overridden attribute', inject(function($compile, $rootScope) {
+      $rootScope.name = "Misko";
+      element = $compile('<span ng-attr-test="{{name}}" test="123"></span>')($rootScope);
+      expect(element.attr('test')).toBe('123');
+      $rootScope.$digest();
+      expect(element.attr('test')).toBe('Misko');
+    }));
+
+
+    describe('in directive', function() {
+      beforeEach(module(function() {
+        directive('syncTest', function(log) {
+          return {
+            link: {
+              pre: function(s, e, attr) { log(attr.test); },
+              post: function(s, e, attr) { log(attr.test); }
+            }
+          };
+        });
+        directive('asyncTest', function(log) {
+          return {
+            templateUrl: 'async.html',
+            link: {
+              pre: function(s, e, attr) { log(attr.test); },
+              post: function(s, e, attr) { log(attr.test); }
+            }
+          };
+        });
+      }));
+
+      beforeEach(inject(function($templateCache) {
+        $templateCache.put('async.html', '<h1>Test</h1>');
+      }));
+
+      it('should provide post-digest value in synchronous directive link functions when after overridden attribute',
+          inject(function(log, $rootScope, $compile) {
+        $rootScope.test = "TEST";
+        element = $compile('<div sync-test test="123" ng-attr-test="{{test}}"></div>')($rootScope);
+        expect(element.attr('test')).toBe('123');
+        expect(log.toArray()).toEqual(['TEST', 'TEST']);
+      }));
+
+      it('should provide post-digest value in synchronous directive link functions when before overridden attribute',
+          inject(function(log, $rootScope, $compile) {
+        $rootScope.test = "TEST";
+        element = $compile('<div sync-test ng-attr-test="{{test}}" test="123"></div>')($rootScope);
+        expect(element.attr('test')).toBe('123');
+        expect(log.toArray()).toEqual(['TEST', 'TEST']);
+      }));
+
+
+      it('should provide post-digest value in asynchronous directive link functions when after overridden attribute',
+          inject(function(log, $rootScope, $compile) {
+        $rootScope.test = "TEST";
+        element = $compile('<div async-test test="123" ng-attr-test="{{test}}"></div>')($rootScope);
+        expect(element.attr('test')).toBe('123');
+        $rootScope.$digest();
+        expect(log.toArray()).toEqual(['TEST', 'TEST']);
+      }));
+
+      it('should provide post-digest value in asynchronous directive link functions when before overridden attribute',
+          inject(function(log, $rootScope, $compile) {
+        $rootScope.test = "TEST";
+        element = $compile('<div async-test ng-attr-test="{{test}}" test="123"></div>')($rootScope);
+        expect(element.attr('test')).toBe('123');
+        $rootScope.$digest();
+        expect(log.toArray()).toEqual(['TEST', 'TEST']);
+      }));
+    });
 
     it('should work with different prefixes', inject(function($compile, $rootScope) {
       $rootScope.name = "Misko";