Make closures optimizable by Crankshaft compiler.

src/hydrogen-instructions.cc

Index: src/hydrogen-instructions.cc
diff --git a/src/hydrogen-instructions.cc b/src/hydrogen-instructions.cc
index 3f39888e9bfbb6dfb547274339b3b5f2c9092412..89478f5e338485300e72f81e4427a1fd2e4027e6 100644
--- a/src/hydrogen-instructions.cc
+++ b/src/hydrogen-instructions.cc
@@ -1190,6 +1190,11 @@ void HStoreGlobal::PrintDataTo(StringStream* stream) const {
 }
 
 
+void HLoadContextSlot::PrintDataTo(StringStream* stream) const {
+  stream->Add("(%d, %d)", context_chain_length(), slot_index());
+}
+
+
 // Implementation of type inference and type conversions. Calculates
 // the inferred type of this instruction based on the input operands.