chore(jenkins): get rid of Opera from the Jenkins build script

The Opera launcher hasn't been installed for ages, but until Karma 1.4.0 the
error of Opera not being able to start was ignored. Karma has fixed the bug and
now Jenkins is failing.

This commit also removes Opera/Opera launcher mentions from the docs. We don't
support Opera officially anymore (it's sort-of supported via being based on
Blink).

Closes #15691

docs/content/misc/contribute.ngdoc

@@ -140,13 +140,13 @@ tests once on Chrome run:
 grunt test:unit
 ```
 
-To run the tests on other browsers (Chrome, ChromeCanary, Firefox, Opera and Safari are pre-configured) use:
+To run the tests on other browsers (Chrome, ChromeCanary, Firefox and Safari are pre-configured) use:
 
 ```shell
-grunt test:unit --browsers=Opera,Firefox
+grunt test:unit --browsers=Chrome,Firefox
 ```
 
-Note there should be _no spaces between browsers_. `Opera, Firefox` is INVALID.
+Note there should be _no spaces between browsers_. `Chrome, Firefox` is INVALID.
 
 During development, however, it's more productive to continuously run unit tests every time the source or test files
 change. To execute tests in this mode run:

scripts/jenkins/build.sh

@@ -12,7 +12,7 @@ set -xe
 # This is the default set of browsers to use on the CI server unless overridden via env variable
 if [[ -z "$BROWSERS" ]]
 then
-  BROWSERS="Chrome,Firefox,Opera,/Users/jenkins/bin/safari.sh"
+  BROWSERS="Chrome,Firefox,/Users/jenkins/bin/safari.sh"
 fi
 
 # CLEAN #

src/ng/browser.js

@@ -255,8 +255,8 @@ function Browser(window, document, $log, $sniffer) {
   self.onUrlChange = function(callback) {
     // TODO(vojta): refactor to use node's syntax for events
     if (!urlChangeInit) {
-      // We listen on both (hashchange/popstate) when available, as some browsers (e.g. Opera)
-      // don't fire popstate when user change the address bar and don't fire hashchange when url
+      // We listen on both (hashchange/popstate) when available, as some browsers don't
+      // fire popstate when user changes the address bar and don't fire hashchange when url
       // changed by push/replaceState
 
       // html5 history api - popstate event

src/ng/urlUtils.js

@@ -20,7 +20,7 @@ var baseUrlParsingNode;
  * URL will be resolved into an absolute URL in the context of the application document.
  * Parsing means that the anchor node's host, hostname, protocol, port, pathname and related
  * properties are all populated to reflect the normalized URL.  This approach has wide
- * compatibility - Safari 1+, Mozilla 1+, Opera 7+,e etc.  See
+ * compatibility - Safari 1+, Mozilla 1+ etc.  See
  * http://www.aptana.com/reference/html/api/HTMLAnchorElement.html
  *
  * Implementation Notes for IE

test/ngMock/angular-mocksSpec.js

@@ -923,7 +923,7 @@ describe('ngMock', function() {
       }));
 
       describe('error stack trace when called outside of spec context', function() {
-        // - Chrome, Firefox, Edge, Opera give us the stack trace as soon as an Error is created
+        // - Chrome, Firefox, Edge give us the stack trace as soon as an Error is created
         // - IE10+, PhantomJS give us the stack trace only once the error is thrown
         // - IE9 does not provide stack traces
         var stackTraceSupported = (function() {