fix($sanitize): don't allow svg animation tags

After angular#11124 got merged, a security vulnerability got introduced.
Animation in SVG became tolerated by the sanitizer.

Exploit Example:
```
<svg>
  <a xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="?">
    <circle r="400"></circle>
    <animate attributeName="xlink:href" begin="0" from="javascript:alert(1)" to="&" />
  </a>
</svg>
```

Here we are animating an anchor's href, starting from a value that's a javascript URI,
allowing the executing of arbitrary javascript in the process.

Preventing only the animation of links is tricky, as SVG is weird and namespaces aren't predictable.
We've decided to have the sanitizer filter out svg animation tags instead.

Considering the sanitizer is commonly used to sanitize untrusted HTML code, this shouldn't affect
many apps in the wild. Also, no release has been with angular#11124 in it, but not this fix.

Author: rodyhaddad

src/ngSanitize/sanitize.js

@@ -206,10 +206,9 @@ var inlineElements = angular.extend({}, optionalEndTagInlineElements, makeMap("a
 
 // SVG Elements
 // https://wiki.whatwg.org/wiki/Sanitization_rules#svg_Elements
-var svgElements = makeMap("animate,animateColor,animateMotion,animateTransform,circle,defs," +
-        "desc,ellipse,font-face,font-face-name,font-face-src,g,glyph,hkern,image,linearGradient," +
-        "line,marker,metadata,missing-glyph,mpath,path,polygon,polyline,radialGradient,rect,set," +
-        "stop,svg,switch,text,title,tspan,use");
+var svgElements = makeMap("circle,defs,desc,ellipse,font-face,font-face-name,font-face-src,g,glyph," +
+        "hkern,image,linearGradient,line,marker,metadata,missing-glyph,mpath,path,polygon,polyline," +
+        "radialGradient,rect,set,stop,svg,switch,text,title,tspan,use");
 
 // Special Elements (can contain anything)
 var specialElements = makeMap("script,style");

test/ngSanitize/sanitizeSpec.js

@@ -273,6 +273,15 @@ describe('HTML', function() {
       .toEqual('<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><a></a></svg>');
   });
 
+  it('should not accept SVG animation tags', function() {
+    expectHTML('<svg xmlns:xlink="http://www.w3.org/1999/xlink"><a><text y="1em">Click me</text><animate attributeName="xlink:href" values="javascript:alert(1)"/></a></svg>')
+      .toEqual('<svg xmlns:xlink="http://www.w3.org/1999/xlink"><a><text y="1em">Click me</text></a></svg>');
+
+    expectHTML('<svg><a xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="?"><circle r="400"></circle>' +
+    '<animate attributeName="xlink:href" begin="0" from="javascript:alert(1)" to="&" /></a></svg>')
+      .toEqual('<svg><a xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="?"><circle r="400"></circle></a></svg>');
+  });
+
   describe('htmlSanitizerWriter', function() {
     /* global htmlSanitizeWriter: false */
     if (angular.isUndefined(window.htmlSanitizeWriter)) return;