Introduce LanguageMode, drop StrictMode.

src/arm64/lithium-arm64.h

Index: src/arm64/lithium-arm64.h
diff --git a/src/arm64/lithium-arm64.h b/src/arm64/lithium-arm64.h
index 5dd39578c775e361e2180394535b09534486b967..8b4872930258a86576d2139af16d7392cf8fb07a 100644
--- a/src/arm64/lithium-arm64.h
+++ b/src/arm64/lithium-arm64.h
@@ -2582,7 +2582,7 @@ class LStoreKeyedGeneric FINAL : public LTemplateInstruction<0, 4, 0> {
 
   void PrintDataTo(StringStream* stream) OVERRIDE;
 
-  StrictMode strict_mode() { return hydrogen()->strict_mode(); }
+  LanguageMode language_mode() { return hydrogen()->language_mode(); }
 };
 
 
@@ -2630,7 +2630,7 @@ class LStoreNamedGeneric FINAL: public LTemplateInstruction<0, 3, 0> {
   void PrintDataTo(StringStream* stream) OVERRIDE;
 
   Handle<Object> name() const { return hydrogen()->name(); }
-  StrictMode strict_mode() { return hydrogen()->strict_mode(); }
+  LanguageMode language_mode() { return hydrogen()->language_mode(); }
 };