VM: Explicitly load function and context before calling a closure.

runtime/vm/flow_graph_compiler.cc

Index: runtime/vm/flow_graph_compiler.cc
===================================================================
--- runtime/vm/flow_graph_compiler.cc	(revision 35546)
+++ runtime/vm/flow_graph_compiler.cc	(working copy)
@@ -471,13 +471,22 @@
 }
 
 
+// Add a lazy deoptimization environment at a call. input_count specifies
+// a number of input operands that will be removed from the environment to
+// match the stack frame layout after the call: Pushed args are present,
+// input operands are consumed before the call.
 void FlowGraphCompiler::AddDeoptIndexAtCall(intptr_t deopt_id,
-                                            intptr_t token_pos) {
+                                            intptr_t token_pos,
+                                            intptr_t input_count) {
   ASSERT(is_optimizing());
+  Environment* env = pending_deoptimization_env_;
+  if (input_count > 0) {
+    env = env->DeepCopy(env->Length() - input_count);
+  }
   CompilerDeoptInfo* info =
       new CompilerDeoptInfo(deopt_id,
                             ICData::kDeoptAtCall,
-                            pending_deoptimization_env_);
+                            env);
   info->set_pc_offset(assembler()->CodeSize());
   deopt_infos_.Add(info);
 }