Introduce LanguageMode, drop StrictMode.

src/runtime/runtime-function.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/accessors.h"
 #include "src/arguments.h"
 #include "src/compiler.h"
 #include "src/deoptimizer.h"
@@ skipping 10 matching lines @@
   if (!callable->IsJSFunction()) {
     HandleScope scope(isolate);
     Handle<Object> delegate;
     ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
         isolate, delegate, Execution::TryGetFunctionDelegate(
                                isolate, Handle<JSReceiver>(callable)));
     callable = JSFunction::cast(*delegate);
   }
   JSFunction* function = JSFunction::cast(callable);
   SharedFunctionInfo* shared = function->shared();
-  return isolate->heap()->ToBoolean(shared->strict_mode() == SLOPPY);
+  return isolate->heap()->ToBoolean(!is_strict(shared->language_mode()));
 }
 
 
 RUNTIME_FUNCTION(Runtime_GetDefaultReceiver) {
   SealHandleScope shs(isolate);
   DCHECK(args.length() == 1);
   CONVERT_ARG_CHECKED(JSReceiver, callable, 0);
 
   if (!callable->IsJSFunction()) {
     HandleScope scope(isolate);
     Handle<Object> delegate;
     ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
         isolate, delegate, Execution::TryGetFunctionDelegate(
                                isolate, Handle<JSReceiver>(callable)));
     callable = JSFunction::cast(*delegate);
   }
   JSFunction* function = JSFunction::cast(callable);
 
   SharedFunctionInfo* shared = function->shared();
-  if (shared->native() || shared->strict_mode() == STRICT) {
+  if (shared->native() || is_strict(shared->language_mode())) {
     return isolate->heap()->undefined_value();
   }
   // Returns undefined for strict or native functions, or
   // the associated global receiver for "normal" functions.
 
   return function->global_proxy();
 }
 
 
 RUNTIME_FUNCTION(Runtime_FunctionGetName) {
@@ skipping 581 matching lines @@
 
 
 RUNTIME_FUNCTION(RuntimeReference_IsFunction) {
   SealHandleScope shs(isolate);
   DCHECK(args.length() == 1);
   CONVERT_ARG_CHECKED(Object, obj, 0);
   return isolate->heap()->ToBoolean(obj->IsJSFunction());
 }
 }
 }  // namespace v8::internal