fix(interpolate): do not create directives for constant media URL attributes

By creating attribute directives that watch the value of
media url attributes (e.g. `img[src]`) we caused a conflict
when both `src` and `data-src` were appearing on the
same element. As each directive was trying to write to the
attributes on the element, where AngularJS treats `src` and
`data-src` as synonymous.

This commit ensures that we do not create create such directives
when the media url attribute is a constant (no interpolation).

Because of this (and because we no longer sanitize URLs in the
`$attr.$set()` method, this commit also updates `ngHref` and
`ngSrc` to do a preliminary sanitization of URLs in case there
is no interpolation in the attribute value.

Fixes #16734

src/ng/directive/attrs.js

@@ -408,7 +408,7 @@ forEach(ALIASED_ATTR, function(htmlAttr, ngAttr) {
 // ng-src, ng-srcset, ng-href are interpolated
 forEach(['src', 'srcset', 'href'], function(attrName) {
   var normalized = directiveNormalize('ng-' + attrName);
-  ngAttributeAliasDirectives[normalized] = function() {
+  ngAttributeAliasDirectives[normalized] = ['$sce', function($sce) {
     return {
       priority: 99, // it needs to run after the attributes are interpolated
       link: function(scope, element, attr) {
@@ -422,6 +422,10 @@ forEach(['src', 'srcset', 'href'], function(attrName) {
           propName = null;
         }
 
+        // We need to sanitize the url at least once, in case it is a constant
+        // non-interpolated attribute.
+        attr.$set(normalized, $sce.getTrustedMediaUrl(attr[normalized]));
+
         attr.$observe(normalized, function(value) {
           if (!value) {
             if (attrName === 'href') {
@@ -441,5 +445,5 @@ forEach(['src', 'srcset', 'href'], function(attrName) {
         });
       }
     };
-  };
+  }];
 });

src/ng/interpolate.js

@@ -242,7 +242,7 @@ function $InterpolateProvider() {
 
       // Provide a quick exit and simplified result function for text with no interpolation
       if (!text.length || text.indexOf(startSymbol) === -1) {
-        if (mustHaveExpression && !contextAllowsConcatenation) return;
+        if (mustHaveExpression) return;
 
         var unescapedText = unescapeText(text);
         if (contextAllowsConcatenation) {

test/ng/compileSpec.js

@@ -3577,6 +3577,15 @@ describe('$compile', function() {
       })
     );
 
+    it('should support non-interpolated `src` and `data-src` on the same element',
+      inject(function($rootScope, $compile) {
+        var element = $compile('<img src="abc" data-src="123">')($rootScope);
+        expect(element.attr('src')).toEqual('abc');
+        expect(element.attr('data-src')).toEqual('123');
+        $rootScope.$digest();
+        expect(element.attr('src')).toEqual('abc');
+        expect(element.attr('data-src')).toEqual('123');
+    }));
 
     it('should call observer only when the attribute value changes', function() {
       module(function() {
@@ -12084,6 +12093,49 @@ describe('$compile', function() {
       expect(element.attr('test6')).toBe('Misko');
     }));
 
+    describe('with media url attributes', function() {
+      it('should work with interpolated ng-attr-src', inject(function() {
+        $rootScope.name = 'some-image.png';
+        element = $compile('<img ng-attr-src="{{name}}">')($rootScope);
+        expect(element.attr('src')).toBeUndefined();
+
+        $rootScope.$digest();
+        expect(element.attr('src')).toBe('some-image.png');
+
+        $rootScope.name = 'other-image.png';
+        $rootScope.$digest();
+        expect(element.attr('src')).toBe('other-image.png');
+      }));
+
+      it('should work with interpolated ng-attr-data-src', inject(function() {
+        $rootScope.name = 'some-image.png';
+        element = $compile('<img ng-attr-data-src="{{name}}">')($rootScope);
+        expect(element.attr('data-src')).toBeUndefined();
+
+        $rootScope.$digest();
+        expect(element.attr('data-src')).toBe('some-image.png');
+
+        $rootScope.name = 'other-image.png';
+        $rootScope.$digest();
+        expect(element.attr('data-src')).toBe('other-image.png');
+      }));
+
+      it('should work alongside constant [src]-attribute and [ng-attr-data-src] attributes', inject(function() {
+        $rootScope.name = 'some-image.png';
+        element = $compile('<img src="constant.png" ng-attr-data-src="{{name}}">')($rootScope);
+        expect(element.attr('data-src')).toBeUndefined();
+
+        $rootScope.$digest();
+        expect(element.attr('src')).toBe('constant.png');
+        expect(element.attr('data-src')).toBe('some-image.png');
+
+        $rootScope.name = 'other-image.png';
+        $rootScope.$digest();
+        expect(element.attr('src')).toBe('constant.png');
+        expect(element.attr('data-src')).toBe('other-image.png');
+      }));
+    });
+
     describe('when an attribute has a dash-separated name', function() {
       it('should work with different prefixes', inject(function() {
         $rootScope.name = 'JamieMason';

test/ng/directive/ngSrcSpec.js

@@ -78,6 +78,20 @@ describe('ngSrc', function() {
         expect(element.prop('src')).toEqual('http://somewhere/abc');
       }));
     }
+
+    it('should work with `src` attribute on the same element', inject(function($rootScope, $compile) {
+      $rootScope.imageUrl = 'dynamic';
+      element = $compile('<img ng-src="{{imageUrl}}" src="static">')($rootScope);
+      expect(element.attr('src')).toBe('static');
+      $rootScope.$digest();
+      expect(element.attr('src')).toBe('dynamic');
+      dealoc(element);
+
+      element = $compile('<img src="static" ng-src="{{imageUrl}}">')($rootScope);
+      expect(element.attr('src')).toBe('static');
+      $rootScope.$digest();
+      expect(element.attr('src')).toBe('dynamic');
+    }));
   });
 
   describe('iframe[ng-src]', function() {