Introduce LanguageMode, drop StrictMode.

src/arm64/lithium-codegen-arm64.cc

Index: src/arm64/lithium-codegen-arm64.cc
diff --git a/src/arm64/lithium-codegen-arm64.cc b/src/arm64/lithium-codegen-arm64.cc
index c49ecb761f51d060e2d524412328f95abb3392b6..e8c12b42ccfa97fefc3d30609cf7ee5ba16d4f96 100644
--- a/src/arm64/lithium-codegen-arm64.cc
+++ b/src/arm64/lithium-codegen-arm64.cc
@@ -662,8 +662,7 @@ bool LCodeGen::GeneratePrologue() {
     // Sloppy mode functions and builtins need to replace the receiver with the
     // global proxy when called as functions (without an explicit receiver
     // object).
-    if (info_->this_has_uses() &&
-        info_->strict_mode() == SLOPPY &&
+    if (info_->this_has_uses() && is_sloppy(info_->language_mode()) &&
         !info_->is_native()) {
       Label ok;
       int receiver_offset = info_->scope()->num_parameters() * kXRegSize;
@@ -2901,7 +2900,7 @@ void LCodeGen::DoFunctionLiteral(LFunctionLiteral* instr) {
   // space for nested functions that don't need literals cloning.
   bool pretenure = instr->hydrogen()->pretenure();
   if (!pretenure && instr->hydrogen()->has_no_literals()) {
-    FastNewClosureStub stub(isolate(), instr->hydrogen()->strict_mode(),
+    FastNewClosureStub stub(isolate(), instr->hydrogen()->language_mode(),
                             instr->hydrogen()->kind());
     __ Mov(x2, Operand(instr->hydrogen()->shared_info()));
     CallCode(stub.GetCode(), RelocInfo::CODE_TARGET, instr);
@@ -5370,7 +5369,7 @@ void LCodeGen::DoStoreKeyedGeneric(LStoreKeyedGeneric* instr) {
   DCHECK(ToRegister(instr->value()).is(StoreDescriptor::ValueRegister()));
 
   Handle<Code> ic =
-      CodeFactory::KeyedStoreIC(isolate(), instr->strict_mode()).code();
+      CodeFactory::KeyedStoreIC(isolate(), instr->language_mode()).code();
   CallCode(ic, RelocInfo::CODE_TARGET, instr);
 }
 
@@ -5480,7 +5479,7 @@ void LCodeGen::DoStoreNamedGeneric(LStoreNamedGeneric* instr) {
   DCHECK(ToRegister(instr->value()).is(StoreDescriptor::ValueRegister()));
 
   __ Mov(StoreDescriptor::NameRegister(), Operand(instr->name()));
-  Handle<Code> ic = StoreIC::initialize_stub(isolate(), instr->strict_mode());
+  Handle<Code> ic = StoreIC::initialize_stub(isolate(), instr->language_mode());
   CallCode(ic, RelocInfo::CODE_TARGET, instr);
 }