Move Promise tracking from debug to isolate.

src/isolate.h

Index: src/isolate.h
diff --git a/src/isolate.h b/src/isolate.h
index 9ef6fc732a9f9f64c22fd4449ce28834a0107083..c0376aeac0bf4a7cf7922daae6603a67265d7f59 100644
--- a/src/isolate.h
+++ b/src/isolate.h
@@ -78,6 +78,7 @@ typedef void* ExternalReferenceRedirectorPointer();
 
 class Debug;
 class Debugger;
+class PromiseOnStack;
 
 #if !defined(__arm__) && V8_TARGET_ARCH_ARM || \
     !defined(__aarch64__) && V8_TARGET_ARCH_ARM64 || \
@@ -240,11 +241,7 @@ class ThreadLocalTop BASE_EMBEDDED {
         v8::TryCatch::JSStackComparableAddress(try_catch_handler()));
   }
 
-  void Free() {
-    DCHECK(!has_pending_message_);
-    DCHECK(!external_caught_exception_);
-    DCHECK(try_catch_handler_ == NULL);
-  }
+  void Free();
 
   Isolate* isolate_;
   // The context where the current execution method is created and for variable
@@ -270,6 +267,11 @@ class ThreadLocalTop BASE_EMBEDDED {
   Address c_entry_fp_;  // the frame pointer of the top c entry frame
   Address handler_;   // try-blocks are chained through the stack
 
+  // Throwing an exception may cause a Promise rejection.  For this purpose
+  // we keep track of a stack of nested promises and the corresponding
+  // try-catch handlers.
+  PromiseOnStack* promise_on_stack_;
+
 #ifdef USE_SIMULATOR
   Simulator* simulator_;
 #endif
@@ -676,6 +678,11 @@ class Isolate {
   // JavaScript code.  If an exception is scheduled true is returned.
   bool OptionalRescheduleException(bool is_bottom_call);
 
+  // Push and pop a promise and the current try-catch handler.
+  void PushPromise(Handle<JSObject> promise);
+  void PopPromise();
+  Handle<Object> GetPromiseOnStackOnThrow();
+
   class ExceptionScope {
    public:
     explicit ExceptionScope(Isolate* isolate) :
@@ -1349,6 +1356,22 @@ class Isolate {
 #undef THREAD_LOCAL_TOP_ACCESSOR
 
 
+class PromiseOnStack {
+ public:
+  PromiseOnStack(StackHandler* handler, Handle<JSObject> promise,
+                 PromiseOnStack* prev)
+      : handler_(handler), promise_(promise), prev_(prev) {}
+  StackHandler* handler() { return handler_; }
+  Handle<JSObject> promise() { return promise_; }
+  PromiseOnStack* prev() { return prev_; }
+
+ private:
+  StackHandler* handler_;
+  Handle<JSObject> promise_;
+  PromiseOnStack* prev_;
+};
+
+
 // If the GCC version is 4.1.x or 4.2.x an additional field is added to the
 // class as a work around for a bug in the generated code found with these
 // versions of GCC. See V8 issue 122 for details.