chore($sniffer) remove Opera < 15 vendor prefixes and document it

Closes #9483

docs/content/misc/faq.ngdoc

@@ -50,7 +50,7 @@ Yes. See instructions in {@link downloading}.
 
 ### What browsers does Angular work with?
 
-We run our extensive test suite against the following browsers: Safari, Chrome, Firefox, Opera,
+We run our extensive test suite against the following browsers: Safari, Chrome, Firefox, Opera 15,
 IE9 and mobile browsers (Android, Chrome Mobile, iOS Safari). See {@link guide/ie Internet
 Explorer Compatibility} for more details in supporting legacy IE browsers.
 

src/ng/sniffer.js

@@ -22,7 +22,7 @@ function $SnifferProvider() {
         boxee = /Boxee/i.test(($window.navigator || {}).userAgent),
         document = $document[0] || {},
         vendorPrefix,
-        vendorRegex = /^(Moz|webkit|O|ms)(?=[A-Z])/,
+        vendorRegex = /^(Moz|webkit|ms)(?=[A-Z])/,
         bodyStyle = document.body && document.body.style,
         transitions = false,
         animations = false,

test/ng/snifferSpec.js

@@ -143,8 +143,7 @@ describe('$sniffer', function() {
           body: {
             style: {
               WebkitAnimation: animationStyle,
-              MozAnimation: animationStyle,
-              OAnimation: animationStyle
+              MozAnimation: animationStyle
             }
           }
         };
@@ -240,8 +239,7 @@ describe('$sniffer', function() {
           body: {
             style: {
               WebkitTransition: transitionStyle,
-              MozTransition: transitionStyle,
-              OTransition: transitionStyle
+              MozTransition: transitionStyle
             }
           }
         };