Fetch global object from jsproxy prototype instead of embedding it in StoreGlobal.

src/code-stubs-hydrogen.cc

Index: src/code-stubs-hydrogen.cc
diff --git a/src/code-stubs-hydrogen.cc b/src/code-stubs-hydrogen.cc
index c679d4c3f56bca0efde13b763756b81216526777..826c1dd730031deef5332b8cbfeb2083d60e939f 100644
--- a/src/code-stubs-hydrogen.cc
+++ b/src/code-stubs-hydrogen.cc
@@ -1313,16 +1313,25 @@ HValue* CodeStubGraphBuilder<StoreGlobalStub>::BuildCodeInitializedStub() {
   Handle<Object> placeholer_value(Smi::FromInt(0), isolate());
   Handle<PropertyCell> placeholder_cell =
       isolate()->factory()->NewPropertyCell(placeholer_value);
-
   HParameter* value = GetParameter(StoreDescriptor::kValueIndex);
-
   if (stub->check_global()) {
     // Check that the map of the global has not changed: use a placeholder map
     // that will be replaced later with the global object's map.
+    HParameter* proxy = GetParameter(StoreDescriptor::kReceiverIndex);
+    HValue* proxy_map =
+        Add<HLoadNamedField>(proxy, nullptr, HObjectAccess::ForMap());
+    HValue* global =
+        Add<HLoadNamedField>(proxy_map, nullptr, HObjectAccess::ForPrototype());
     Handle<Map> placeholder_map = isolate()->factory()->meta_map();
-    HValue* global = Add<HConstant>(
-        StoreGlobalStub::global_placeholder(isolate()));
-    Add<HCheckMaps>(global, placeholder_map);
+    HValue* cell = Add<HConstant>(Map::WeakCellForMap(placeholder_map));
+    HValue* expected_map =
+        Add<HLoadNamedField>(cell, nullptr, HObjectAccess::ForWeakCellValue());
+    HValue* map =
+        Add<HLoadNamedField>(global, nullptr, HObjectAccess::ForMap());
+    IfBuilder map_check(this);
+    map_check.IfNot<HCompareObjectEqAndBranch>(expected_map, map);
+    map_check.ThenDeopt("Unknown map");
+    map_check.End();
   }
 
   HValue* cell = Add<HConstant>(placeholder_cell);