Enable extra API checks, add a check for zapped global handles

Review URL: https://codereview.chromium.org/12833015

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@14024 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

build/common.gypi

@@ -401,7 +401,7 @@
       },  # Debug
       'Release': {
         'variables': {
-          'v8_enable_extra_checks%': 0,
+          'v8_enable_extra_checks%': 1,
         },
         'conditions': [
           ['v8_enable_extra_checks==1', {

src/api.h

@@ -294,6 +294,9 @@ MAKE_TO_LOCAL(ToLocal, DeclaredAccessorDescriptor, DeclaredAccessorDescriptor)
   v8::internal::Handle<v8::internal::To> Utils::OpenHandle(                 \
     const v8::From* that, bool allow_empty_handle) {                        \
     EXTRA_CHECK(allow_empty_handle || that != NULL);                        \
+    EXTRA_CHECK(that == NULL ||                                             \
+        !(*reinterpret_cast<v8::internal::To**>(                            \
+            const_cast<v8::From*>(that)))->IsFailure());                    \
     return v8::internal::Handle<v8::internal::To>(                          \
         reinterpret_cast<v8::internal::To**>(const_cast<v8::From*>(that))); \
   }