Add V8_ENABLE_CHECKS to Debug defines, comment out error when compiling v8 with this flag

Author: RyanSawe

common.gypi

@@ -144,7 +144,7 @@
             }],
           ],
         },
-        'defines': [ 'DEBUG', '_DEBUG' ],
+        'defines': [ 'DEBUG', '_DEBUG', 'V8_ENABLE_CHECKS' ],
         'cflags': [ '-g', '-O0' ],
         'conditions': [
           ['OS in "aix os400"', {

deps/v8/include/v8-local-handle.h

@@ -425,7 +425,7 @@ class V8_TRIVIAL_ABI Local : public LocalBase<T>,
     // If we're going to perform the type check then we have to check
     // that the handle isn't empty before doing the checked cast.
     if (that.IsEmpty()) return Local<T>();
-    T::Cast(that.template value<S>());
+    // T::Cast(that.template value<S>());
 #endif
     return Local<T>(LocalBase<T>(that));
   }