Add ASSERT(isMainThread()) to WorkerThread::start() and ::terminate()

Source/core/workers/WorkerThread.cpp

Index: Source/core/workers/WorkerThread.cpp
diff --git a/Source/core/workers/WorkerThread.cpp b/Source/core/workers/WorkerThread.cpp
index ee06a089949d8c1f193bb1558b17f2e439fa86d6..7a70be8bb4a16562755b2bebd71e0c2c60e83426 100644
--- a/Source/core/workers/WorkerThread.cpp
+++ b/Source/core/workers/WorkerThread.cpp
@@ -177,6 +177,7 @@ WorkerThread::~WorkerThread()
 
 void WorkerThread::start(PassOwnPtr<WorkerThreadStartupData> startupData)
 {
+    ASSERT(isMainThread());
     if (m_started)
         return;
 
@@ -288,6 +289,7 @@ void WorkerThread::shutdown()
 
 void WorkerThread::terminate()
 {
+    ASSERT(isMainThread());

[kinuko, 2015/06/12 05:48:03]

Should this rather be in terminateInternal() ?

[Takashi Toyoshima, 2015/06/15 05:01:03]

Done.

     // Prevent the deadlock between GC and an attempt to terminate a thread.
     SafePointScope safePointScope(ThreadState::HeapPointersOnStack);
     terminateInternal();