Reland of Clear LifecycleObserver::m_context when LifecycleObserver::contextDestroyed gets called

third_party/WebKit/Source/modules/fetch/Body.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "modules/fetch/Body.h"
 
 #include "bindings/core/v8/ScriptPromiseResolver.h"
 #include "bindings/core/v8/ScriptState.h"
 #include "bindings/core/v8/V8ArrayBuffer.h"
 #include "bindings/core/v8/V8ThrowException.h"
@@ skipping 193 matching lines @@
     return bodyBuffer() && bodyBuffer()->isStreamDisturbed();
 }
 
 bool Body::isBodyLocked()
 {
     return bodyBuffer() && bodyBuffer()->isStreamLocked();
 }
 
 bool Body::hasPendingActivity() const
 {
-    if (getExecutionContext()->activeDOMObjectsAreStopped())
+    if (!getExecutionContext() || getExecutionContext()->activeDOMObjectsAreStopped())
         return false;
     if (!bodyBuffer())
         return false;
     return bodyBuffer()->hasPendingActivity();
 }
 
 Body::Body(ExecutionContext* context) : ActiveScriptWrappable(this) , ContextLifecycleObserver(context) {}
 
 ScriptPromise Body::rejectInvalidConsumption(ScriptState* scriptState)
 {
     if (isBodyLocked() || bodyUsed())
         return ScriptPromise::reject(scriptState, V8ThrowException::createTypeError(scriptState->isolate(), "Already read"));
     return ScriptPromise();
 }
 
 } // namespace blink