Make saving and restoring of the context around closure calls explicit.

vm/flow_graph_builder.cc

Index: vm/flow_graph_builder.cc
===================================================================
--- vm/flow_graph_builder.cc	(revision 7782)
+++ vm/flow_graph_builder.cc	(working copy)
@@ -1371,12 +1371,8 @@
 }
 
 
-void EffectGraphVisitor::VisitClosureCallNode(ClosureCallNode* node) {
-  // Context is saved around the call, it's treated as an extra operand
-  // consumed by the call (but not an argument).
-  BindInstr* context = new BindInstr(new CurrentContextComp());
-  AddInstruction(context);
-
+ClosureCallComp* EffectGraphVisitor::BuildClosureCall(
+    ClosureCallNode* node) {
   ValueGraphVisitor for_closure(owner(), temp_index());
   node->closure()->Visit(&for_closure);
   Append(for_closure);
@@ -1385,15 +1381,34 @@
       new ZoneGrowableArray<Value*>(node->arguments()->length());
   arguments->Add(for_closure.value());
   TranslateArgumentList(*node->arguments(), arguments);
-  // First operand is the saved context, consumed by the call.
-  ClosureCallComp* call =  new ClosureCallComp(node,
-                                               owner()->try_index(),
-                                               new UseVal(context),
-                                               arguments);
-  ReturnComputation(call);
+
+  // Save context around the call.
+  BuildStoreContext(*owner()->parsed_function().expression_temp_var());
+  return new ClosureCallComp(node, owner()->try_index(), arguments);
 }
 
 
+void EffectGraphVisitor::VisitClosureCallNode(ClosureCallNode* node) {
+  ClosureCallComp* call = BuildClosureCall(node);
+  AddInstruction(new DoInstr(call));
+
+  // Restore context from saved location.
+  BuildLoadContext(*owner()->parsed_function().expression_temp_var());
+}
+
+
+void ValueGraphVisitor::VisitClosureCallNode(ClosureCallNode* node) {
+  ClosureCallComp* call = BuildClosureCall(node);
+  BindInstr* result = new BindInstr(call);
+  AddInstruction(result);
+
+  // Restore context from temp.
+  BuildLoadContext(*owner()->parsed_function().expression_temp_var());
+
+  ReturnValue(new UseVal(result));
+}
+
+
 void EffectGraphVisitor::VisitCloneContextNode(CloneContextNode* node) {
   BindInstr* context = new BindInstr(new CurrentContextComp());
   AddInstruction(context);