Add HLoadRoot hydrogen instruction.

src/ia32/lithium-ia32.cc

Index: src/ia32/lithium-ia32.cc
diff --git a/src/ia32/lithium-ia32.cc b/src/ia32/lithium-ia32.cc
index 77f5706c6f803c07c63d9ccf44794c049375d6bd..abc7d6c24d298ba1394903bf3998ec81178b48c9 100644
--- a/src/ia32/lithium-ia32.cc
+++ b/src/ia32/lithium-ia32.cc
@@ -2208,6 +2208,11 @@ LInstruction* LChunkBuilder::DoLoadFunctionPrototype(
 }
 
 
+LInstruction* LChunkBuilder::DoLoadRoot(HLoadRoot* instr) {
+  return DefineAsRegister(new(zone()) LLoadRoot);
+}
+
+
 LInstruction* LChunkBuilder::DoLoadExternalArrayPointer(
     HLoadExternalArrayPointer* instr) {
   LOperand* input = UseRegisterAtStart(instr->value());