Introduce per-isolate assert scopes and API to guard JS execution.

src/heap-inl.h

Index: src/heap-inl.h
diff --git a/src/heap-inl.h b/src/heap-inl.h
index ea175bbc3b5c8cffa5b5e673c25fc468d4f62745..459be609a66eec14728113f5150baccb438707d7 100644
--- a/src/heap-inl.h
+++ b/src/heap-inl.h
@@ -223,7 +223,7 @@ MaybeObject* Heap::AllocateRaw(int size_in_bytes,
   HeapProfiler* profiler = isolate_->heap_profiler();
 #ifdef DEBUG
   if (FLAG_gc_interval >= 0 &&
-      !disallow_allocation_failure_ &&
+      AllowAllocationFailure::IsAllowed(isolate_) &&
       Heap::allocation_timeout_-- <= 0) {
     return Failure::RetryAfterGC(space);
   }
@@ -663,7 +663,7 @@ Isolate* Heap::isolate() {
     (ISOLATE)->counters()->gc_last_resort_from_handles()->Increment();         \
     (ISOLATE)->heap()->CollectAllAvailableGarbage("last resort gc");           \
     {                                                                          \
-      AlwaysAllocateScope __scope__;                                           \
+      AlwaysAllocateScope __scope__(ISOLATE);                                  \
       __maybe_object__ = FUNCTION_CALL;                                        \
     }                                                                          \
     if (__maybe_object__->ToObject(&__object__)) RETURN_VALUE;                 \
@@ -778,21 +778,20 @@ void Heap::CompletelyClearInstanceofCache() {
 }
 
 
-AlwaysAllocateScope::AlwaysAllocateScope() {
+AlwaysAllocateScope::AlwaysAllocateScope(Isolate* isolate)
+    : heap_(isolate->heap()), daf_(isolate) {
   // We shouldn't hit any nested scopes, because that requires
   // non-handle code to call handle code. The code still works but
   // performance will degrade, so we want to catch this situation
   // in debug mode.
-  Isolate* isolate = Isolate::Current();
-  ASSERT(isolate->heap()->always_allocate_scope_depth_ == 0);
-  isolate->heap()->always_allocate_scope_depth_++;
+  ASSERT(heap_->always_allocate_scope_depth_ == 0);
+  heap_->always_allocate_scope_depth_++;
 }
 
 
 AlwaysAllocateScope::~AlwaysAllocateScope() {
-  Isolate* isolate = Isolate::Current();
-  isolate->heap()->always_allocate_scope_depth_--;
-  ASSERT(isolate->heap()->always_allocate_scope_depth_ == 0);
+  heap_->always_allocate_scope_depth_--;
+  ASSERT(heap_->always_allocate_scope_depth_ == 0);
 }
 
 
@@ -833,23 +832,6 @@ double GCTracer::SizeOfHeapObjects() {
 }
 
 
-DisallowAllocationFailure::DisallowAllocationFailure() {
-#ifdef DEBUG
-  Isolate* isolate = Isolate::Current();
-  old_state_ = isolate->heap()->disallow_allocation_failure_;
-  isolate->heap()->disallow_allocation_failure_ = true;
-#endif
-}
-
-
-DisallowAllocationFailure::~DisallowAllocationFailure() {
-#ifdef DEBUG
-  Isolate* isolate = Isolate::Current();
-  isolate->heap()->disallow_allocation_failure_ = old_state_;
-#endif
-}
-
-
 } }  // namespace v8::internal
 
 #endif  // V8_HEAP_INL_H_