harmony-scoping: Implement LoadIC handler for loads from global contexts.

src/hydrogen-instructions.cc

Index: src/hydrogen-instructions.cc
diff --git a/src/hydrogen-instructions.cc b/src/hydrogen-instructions.cc
index ce76fbecac93a909854dfe53c8604e52a170f06e..53daf5372ba2948dac6bca374faedb0fbb10ebf9 100644
--- a/src/hydrogen-instructions.cc
+++ b/src/hydrogen-instructions.cc
@@ -4641,6 +4641,14 @@ HObjectAccess HObjectAccess::ForContextSlot(int index) {
 }
 
 
+HObjectAccess HObjectAccess::ForGlobalContext(int index) {
+  DCHECK(index >= 0);
+  Portion portion = kInobject;
+  int offset = GlobalContextTable::GetContextOffset(index);
+  return HObjectAccess(portion, offset, Representation::Tagged());
+}
+
+
 HObjectAccess HObjectAccess::ForJSArrayOffset(int offset) {
   DCHECK(offset >= 0);
   Portion portion = kInobject;