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

src/mips/full-codegen-mips.cc

Index: src/mips/full-codegen-mips.cc
diff --git a/src/mips/full-codegen-mips.cc b/src/mips/full-codegen-mips.cc
index 14d98e395b2b9b6e4c1023bbea667b93f4545080..b78c78332eb5370df91969b841df1dfd18eb45ed 100644
--- a/src/mips/full-codegen-mips.cc
+++ b/src/mips/full-codegen-mips.cc
@@ -192,10 +192,13 @@ 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 a1.
+    Comment cmnt(masm_, "[ Allocate context");
+    // Argument to NewContext is the function, which is still in a1.
     __ push(a1);
-    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 {