Assume that addEventListener/removeEventListener are present in browsers

Jasmine 3.0 dropped support for the last browser that didn't support
the standard event handler methods (IE 9).

src/core/GlobalErrors.js

@@ -109,21 +109,14 @@ getJasmineRequireObj().GlobalErrors = function(j$) {
           }
         };
 
-        if (global.addEventListener) {
-          global.addEventListener(
-            'unhandledrejection',
-            browserRejectionHandler
-          );
-        }
+        global.addEventListener('unhandledrejection', browserRejectionHandler);
 
         this.uninstall = function uninstall() {
           global.onerror = originalHandler;
-          if (global.removeEventListener) {
-            global.removeEventListener(
-              'unhandledrejection',
-              browserRejectionHandler
-            );
-          }
+          global.removeEventListener(
+            'unhandledrejection',
+            browserRejectionHandler
+          );
         };
       }
     };