Revert of Fix leaks when the shared worker is requested to be terminated while...

Revert of Fix leaks when the shared worker is requested to be terminated while loading the main script. (https://codereview.chromium.org/451603002/)

Reason for revert:
UAF bug in WebSharedWorkerImpl::stopWorkerThread().

Original issue's description:
> Fix leaks when the shared worker is requested to be terminated while loading the main script.
> 
> BUG=398742
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=180013

TBR=jochen@chromium.org,sigbjornf@opera.com
NOTREECHECKS=true
NOTRY=true
BUG=398742

Review URL: https://codereview.chromium.org/465863002

git-svn-id: svn://svn.chromium.org/blink/trunk@180031 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/LayoutTests/LeakExpectations

@@ -55,6 +55,10 @@ crbug.com/385384 fast/dom/navigator-detached-no-crash.html [ Leak ]
 # Untriaged but known leaks which may be false positives.
 # -----------------------------------------------------------------
 
+crbug.com/398742 fast/workers/shared-worker-event-listener.html [ Leak ]
+crbug.com/398742 fast/workers/worker-crash-with-invalid-location.html [ Leak ]
+crbug.com/398742 http/tests/security/contentSecurityPolicy/1.1/child-src/worker-shared-allowed.html [ Leak ]
+
 crbug.com/364408 inspector/extensions/extensions-audits-content-script.html [ Leak ]
 crbug.com/364408 inspector/extensions/extensions-eval-content-script.html [ Leak ]
 crbug.com/364408 inspector/extensions/extensions-reload.html [ Leak ]

third_party/WebKit/Source/web/WebSharedWorkerImpl.cpp

@@ -182,9 +182,6 @@ void WebSharedWorkerImpl::stopWorkerThread()
     if (m_mainScriptLoader) {
         m_mainScriptLoader->cancel();
         m_mainScriptLoader.clear();
-        if (client())
-            client()->workerScriptLoadFailed();
-        delete this;
     }
     if (m_workerThread)
         m_workerThread->stop();
@@ -350,16 +347,17 @@ void WebSharedWorkerImpl::onScriptLoaderFinished()
 {
     ASSERT(m_loadingDocument);
     ASSERT(m_mainScriptLoader);
-    if (m_askedToTerminate)
-        return;
-    if (m_mainScriptLoader->failed()) {
+    if (m_mainScriptLoader->failed() || m_askedToTerminate) {
         m_mainScriptLoader->cancel();
         if (client())
             client()->workerScriptLoadFailed();
 
         // The SharedWorker was unable to load the initial script, so
-        // shut it down right here.
-        delete this;
+        // shut it down right here unless we're here handling a load
+        // cancellation failure triggered by an explicit shared worker
+        // termination call (via terminateWorkerContext().)
+        if (!m_askedToTerminate)
+            delete this;
         return;
     }
     WorkerThreadStartMode startMode = m_pauseWorkerContextOnStart ? PauseWorkerGlobalScopeOnStart : DontPauseWorkerGlobalScopeOnStart;