Add optimized compiler support for generic global loads....

src/x64/lithium-x64.h

Index: src/x64/lithium-x64.h
===================================================================
--- src/x64/lithium-x64.h	(revision 7145)
+++ src/x64/lithium-x64.h	(working copy)
@@ -118,6 +118,7 @@
   V(LoadElements)                               \
   V(LoadExternalArrayPointer)                   \
   V(LoadGlobal)                                 \
+  V(LoadGlobalGeneric)                          \
   V(LoadKeyedFastElement)                       \
   V(LoadKeyedGeneric)                           \
   V(LoadNamedField)                             \
@@ -1231,6 +1232,13 @@
 };
 
 
+class LLoadGlobalGeneric: public LTemplateInstruction<1, 0, 0> {
+ public:
+  DECLARE_CONCRETE_INSTRUCTION(LoadGlobalGeneric, "load-global-generic")
+  DECLARE_HYDROGEN_ACCESSOR(LoadGlobalGeneric)
+};
+
+
 class LStoreGlobal: public LTemplateInstruction<0, 1, 1> {
  public:
   explicit LStoreGlobal(LOperand* value, LOperand* temp) {