Add HLoadRoot hydrogen instruction.

src/arm/lithium-arm.h

Index: src/arm/lithium-arm.h
diff --git a/src/arm/lithium-arm.h b/src/arm/lithium-arm.h
index 94b5e2a07a81673510021d0fcbacc36e3921314c..1add1598025c653f961f1b2f99634d6b39db60a6 100644
--- a/src/arm/lithium-arm.h
+++ b/src/arm/lithium-arm.h
@@ -120,6 +120,7 @@ class LCodeGen;
   V(LazyBailout)                                \
   V(LoadContextSlot)                            \
   V(LoadExternalArrayPointer)                   \
+  V(LoadRoot)                                   \
   V(LoadFieldByIndex)                           \
   V(LoadFunctionPrototype)                      \
   V(LoadGlobalCell)                             \
@@ -1593,6 +1594,15 @@ class LLoadFunctionPrototype V8_FINAL : public LTemplateInstruction<1, 1, 0> {
 };
 
 
+class LLoadRoot V8_FINAL : public LTemplateInstruction<1, 0, 0> {
+ public:
+  DECLARE_CONCRETE_INSTRUCTION(LoadRoot, "load-root")
+  DECLARE_HYDROGEN_ACCESSOR(LoadRoot)
+
+  Heap::RootListIndex index() const { return hydrogen()->index(); }
+};
+
+
 class LLoadExternalArrayPointer V8_FINAL
     : public LTemplateInstruction<1, 1, 0> {
  public: