Introduce LanguageMode, drop StrictMode.

src/full-codegen.cc

Index: src/full-codegen.cc
diff --git a/src/full-codegen.cc b/src/full-codegen.cc
index cc32c3e31fa50b5fd8e3601d69869dcc4187a56e..7d4fa64ff66672ccd20f2b755f91092123edc7ae 100644
--- a/src/full-codegen.cc
+++ b/src/full-codegen.cc
@@ -447,7 +447,7 @@ void FullCodeGenerator::CallLoadIC(ContextualMode contextual_mode,
 
 
 void FullCodeGenerator::CallStoreIC(TypeFeedbackId id) {
-  Handle<Code> ic = CodeFactory::StoreIC(isolate(), strict_mode()).code();
+  Handle<Code> ic = CodeFactory::StoreIC(isolate(), language_mode()).code();
   CallIC(ic, id);
 }
 
@@ -814,10 +814,10 @@ void FullCodeGenerator::VisitModuleUrl(ModuleUrl* module) {
 
 
 int FullCodeGenerator::DeclareGlobalsFlags() {
-  DCHECK(DeclareGlobalsStrictMode::is_valid(strict_mode()));
+  DCHECK(DeclareGlobalsLanguageMode::is_valid(language_mode()));
   return DeclareGlobalsEvalFlag::encode(is_eval()) |
-      DeclareGlobalsNativeFlag::encode(is_native()) |
-      DeclareGlobalsStrictMode::encode(strict_mode());
+         DeclareGlobalsNativeFlag::encode(is_native()) |
+         DeclareGlobalsLanguageMode::encode(language_mode());
 }