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

src/x64/lithium-x64.cc

Index: src/x64/lithium-x64.cc
===================================================================
--- src/x64/lithium-x64.cc	(revision 7145)
+++ src/x64/lithium-x64.cc	(working copy)
@@ -1714,6 +1714,12 @@
 }
 
 
+LInstruction* LChunkBuilder::DoLoadGlobalGeneric(HLoadGlobalGeneric* instr) {
+  LLoadGlobalGeneric* result = new LLoadGlobalGeneric;
+  return MarkAsCall(DefineFixed(result, rax), instr);
+}
+
+
 LInstruction* LChunkBuilder::DoStoreGlobal(HStoreGlobal* instr) {
   LStoreGlobal* result = new LStoreGlobal(UseRegister(instr->value()),
                                           TempRegister());