Introduce global contexts to represent lexical global scope(s).

src/arm/full-codegen-arm.cc

Index: src/arm/full-codegen-arm.cc
diff --git a/src/arm/full-codegen-arm.cc b/src/arm/full-codegen-arm.cc
index 716f78dc1ba4d67d9250e13077e11747a45c4499..f2b195ec9843420a0e6c2011fa2ab043a3caa006 100644
--- a/src/arm/full-codegen-arm.cc
+++ b/src/arm/full-codegen-arm.cc
@@ -184,10 +184,13 @@ void FullCodeGenerator::Generate() {
   // Possibly allocate a local context.
   int heap_slots = info->scope()->num_heap_slots() - Context::MIN_CONTEXT_SLOTS;
   if (heap_slots > 0) {
-    Comment cmnt(masm_, "[ Allocate local context");
-    // Argument to NewContext is the function, which is in r1.
+    // Argument to NewContext is the function, which is still in r1.
+    Comment cmnt(masm_, "[ Allocate context");
     __ push(r1);
-    if (heap_slots <= FastNewContextStub::kMaximumSlots) {
+    if (FLAG_harmony_scoping && info->scope()->is_global_scope()) {
+      __ Push(info->scope()->GetScopeInfo());
+      __ CallRuntime(Runtime::kNewGlobalContext, 2);
+    } else if (heap_slots <= FastNewContextStub::kMaximumSlots) {
       FastNewContextStub stub(heap_slots);
       __ CallStub(&stub);
     } else {