[e2e] Remove obsolete legacy e2e test

This CL removes the JS side of the 'testPauseWhenScriptIsRunning'
legacy test.

This test is replaced with a e2e test in https://crrev.com/c/3867522.
The Chromium code was removed with https://crrev.com/c/3868727.

R=kimanh@chromium.org

Bug: 1246907,1289529
Change-Id: I32e68d3fe56c1f78eaef10846418f3246dd8536a
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/3867524
Reviewed-by: Kim-Anh Tran <kimanh@chromium.org>
Commit-Queue: Simon Zünd <szuend@chromium.org>

front_end/Tests.js

@@ -353,31 +353,6 @@
     this.takeControl();
   };
 
-  // Tests that pressing "Pause" will pause script execution if the script
-  // is already running.
-  TestSuite.prototype.testPauseWhenScriptIsRunning = function() {
-    this.showPanel('sources').then(function() {
-      this.evaluateInConsole_('setTimeout("handleClick()", 0)', didEvaluateInConsole.bind(this));
-    }.bind(this));
-
-    function didEvaluateInConsole(resultText) {
-      this.assertTrue(!isNaN(resultText), 'Failed to get timer id: ' + resultText);
-      // Wait for some time to make sure that inspected page is running the
-      // infinite loop.
-      setTimeout(testScriptPause.bind(this), 300);
-    }
-
-    function testScriptPause() {
-      // The script should be in infinite loop. Click "Pause" button to
-      // pause it and wait for the result.
-      UI.panels.sources.togglePause();
-
-      this._waitForScriptPause(this.releaseControl.bind(this));
-    }
-
-    this.takeControl();
-  };
-
   /**
    * Tests network size.
    */