A64: Synchronize with r17635.

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 27730cab167e4b9a506a62cc069133a0009f4243..7bb5e8b9baca6b6c4634c127d2cdcbf734b7c687 100644
--- a/src/a64/code-stubs-a64.cc
+++ b/src/a64/code-stubs-a64.cc
@@ -329,6 +329,19 @@ void ElementsTransitionAndStoreStub::InitializeInterfaceDescriptor(
 }
 
 
+void NewStringAddStub::InitializeInterfaceDescriptor(
+    Isolate* isolate,
+    CodeStubInterfaceDescriptor* descriptor) {
+  // x1: left operand
+  // x0: right operand
+  static Register registers[] = { x1, x0 };
+  descriptor->register_param_count_ = sizeof(registers) / sizeof(registers[0]);
+  descriptor->register_params_ = registers;
+  descriptor->deoptimization_handler_ =
+      Runtime::FunctionForId(Runtime::kStringAdd)->entry;
+}
+
+
 #define __ ACCESS_MASM(masm)