Turn StringLengthStub (used by string wrappers only) into a hydrogen stub.

src/a64/code-stubs-a64.cc

Index: src/a64/code-stubs-a64.cc
diff --git a/src/a64/code-stubs-a64.cc b/src/a64/code-stubs-a64.cc
index d3d169387b29db3a6c015895386fa664cf9eae61..6a74e7ad0e12ae3de8c0afa4740edec426cba982 100644
--- a/src/a64/code-stubs-a64.cc
+++ b/src/a64/code-stubs-a64.cc
@@ -187,6 +187,26 @@ void KeyedLoadFieldStub::InitializeInterfaceDescriptor(
 }
 
 
+void StringLengthStub::InitializeInterfaceDescriptor(
+    Isolate* isolate,
+    CodeStubInterfaceDescriptor* descriptor) {
+  static Register registers[] = { x0, x2 };
+  descriptor->register_param_count_ = 2;
+  descriptor->register_params_ = registers;
+  descriptor->deoptimization_handler_ = NULL;
+}
+
+
+void KeyedStringLengthStub::InitializeInterfaceDescriptor(
+    Isolate* isolate,
+    CodeStubInterfaceDescriptor* descriptor) {
+  static Register registers[] = { x1, x0 };
+  descriptor->register_param_count_ = 2;
+  descriptor->register_params_ = registers;
+  descriptor->deoptimization_handler_ = NULL;
+}
+
+
 void KeyedStoreFastElementStub::InitializeInterfaceDescriptor(
     Isolate* isolate,
     CodeStubInterfaceDescriptor* descriptor) {
@@ -1969,38 +1989,6 @@ void FunctionPrototypeStub::Generate(MacroAssembler* masm) {
 }
 
 
-void StringLengthStub::Generate(MacroAssembler* masm) {
-  Label miss;
-  Register receiver;
-  if (kind() == Code::KEYED_LOAD_IC) {
-    // ----------- S t a t e -------------
-    //  -- lr    : return address
-    //  -- x1    : receiver
-    //  -- x0    : key
-    // -----------------------------------
-    Register key = x0;
-    receiver = x1;
-    __ Cmp(key, Operand(masm->isolate()->factory()->length_string()));
-    __ B(ne, &miss);
-  } else {
-    ASSERT(kind() == Code::LOAD_IC);
-    // ----------- S t a t e -------------
-    //  -- lr    : return address
-    //  -- x2    : name
-    //  -- x0    : receiver
-    //  -- sp[0] : receiver
-    // -----------------------------------
-    receiver = x0;
-  }
-
-  StubCompiler::GenerateLoadStringLength(masm, receiver, x10, x11, &miss);
-
-  __ Bind(&miss);
-  StubCompiler::TailCallBuiltin(masm,
-                                BaseLoadStoreStubCompiler::MissBuiltin(kind()));
-}
-
-
 void StoreArrayLengthStub::Generate(MacroAssembler* masm) {
   ASM_LOCATION("StoreArrayLengthStub::Generate");
   // This accepts as a receiver anything JSArray::SetElementsLength accepts