Introduce API to trigger exception on JS execution.

include/v8.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 4072 matching lines @@
     Scope(const Scope&);
     Scope& operator=(const Scope&);
   };
 
 
   /**
    * Assert that no Javascript code is invoked.
    */
   class DisallowJavascriptExecutionScope {
    public:
-    explicit DisallowJavascriptExecutionScope(Isolate* isolate);
+    enum OnFailure { CRASH_ON_FAILURE, THROW_ON_FAILURE };
+
+    explicit DisallowJavascriptExecutionScope(Isolate* isolate,
+                                              OnFailure on_failure);
     ~DisallowJavascriptExecutionScope();
 
    private:
+    bool on_failure_;
     void* internal_;
 
     // Prevent copying of Scope objects.
     DisallowJavascriptExecutionScope(const DisallowJavascriptExecutionScope&);
     DisallowJavascriptExecutionScope& operator=(
         const DisallowJavascriptExecutionScope&);
   };
 
 
   /**
    * Introduce exception to DisallowJavascriptExecutionScope.
    */
   class AllowJavascriptExecutionScope {
    public:
     explicit AllowJavascriptExecutionScope(Isolate* isolate);
     ~AllowJavascriptExecutionScope();
 
    private:
-    void* internal_;
+    void* internal_throws_;
+    void* internal_assert_;
+
+    // Prevent copying of Scope objects.
+    AllowJavascriptExecutionScope(const AllowJavascriptExecutionScope&);
+    AllowJavascriptExecutionScope& operator=(
+        const AllowJavascriptExecutionScope&);
   };
 
   /**
    * Types of garbage collections that can be requested via
    * RequestGarbageCollectionForTesting.
    */
   enum GarbageCollectionType {
     kFullGarbageCollection,
     kMinorGarbageCollection
   };
@@ skipping 2447 matching lines @@
  */
 
 
 }  // namespace v8
 
 
 #undef TYPE_CHECK
 
 
 #endif  // V8_H_