Bug 1359245 - Keep a linked list of CycleCollectedJSContexts in the runtime (r=mccr8)

This patch keeps a list of all the cooperatively scheduled contexts that are
linked to a runtime. In places where we need to iterate over all contexts (for
GC, specifically), it iterates over the list.

MozReview-Commit-ID: 3pKJX78f2l0

xpcom/base/CycleCollectedJSContext.cpp

@@ -69,6 +69,8 @@ CycleCollectedJSContext::~CycleCollectedJSContext()
     return;
   }
 
+  mRuntime->RemoveContext(this);
+
   if (mIsPrimaryContext) {
     mRuntime->Shutdown(mJSContext);
   }
@@ -112,6 +114,8 @@ CycleCollectedJSContext::~CycleCollectedJSContext()
 void
 CycleCollectedJSContext::InitializeCommon()
 {
+  mRuntime->AddContext(this);
+
   mOwningThread->SetScriptObserver(this);
   // The main thread has a base recursion depth of 0, workers of 1.
   mBaseRecursionDepth = RecursionDepth();