Introduce a hydrogen value for contexts, support context slot assignment.

src/x64/lithium-x64.cc

Index: src/x64/lithium-x64.cc
diff --git a/src/x64/lithium-x64.cc b/src/x64/lithium-x64.cc
index 0a52c6da18ff03ba5dfdee63691cfe405c40454c..b9bc6e0f0327f03a8f8fba70bb79c449417b098e 100644
--- a/src/x64/lithium-x64.cc
+++ b/src/x64/lithium-x64.cc
@@ -262,7 +262,8 @@ void LUnaryMathOperation::PrintDataTo(StringStream* stream) {
 
 
 void LLoadContextSlot::PrintDataTo(StringStream* stream) {
-  stream->Add("(%d, %d)", context_chain_length(), slot_index());
+  InputAt(0)->PrintTo(stream);
+  stream->Add("[%d]", slot_index());
 }
 
 
@@ -1049,6 +1050,18 @@ LInstruction* LChunkBuilder::DoPushArgument(HPushArgument* instr) {
 }
 
 
+LInstruction* LChunkBuilder::DoContext(HContext* instr) {
+  Abort("Unimplemented: DoContext");
+  return NULL;
+}
+
+
+LInstruction* LChunkBuilder::DoOuterContext(HOuterContext* instr) {
+  Abort("Unimplemented: DoOuterContext");
+  return NULL;
+}
+
+
 LInstruction* LChunkBuilder::DoGlobalObject(HGlobalObject* instr) {
   return DefineAsRegister(new LGlobalObject);
 }
@@ -1472,7 +1485,8 @@ LInstruction* LChunkBuilder::DoLoadGlobal(HLoadGlobal* instr) {
 
 
 LInstruction* LChunkBuilder::DoStoreGlobal(HStoreGlobal* instr) {
-  return new LStoreGlobal(UseRegisterAtStart(instr->value()));}
+  return new LStoreGlobal(UseRegisterAtStart(instr->value()));
+}
 
 
 LInstruction* LChunkBuilder::DoLoadContextSlot(HLoadContextSlot* instr) {
@@ -1481,6 +1495,12 @@ LInstruction* LChunkBuilder::DoLoadContextSlot(HLoadContextSlot* instr) {
 }
 
 
+LInstruction* LChunkBuilder::DoStoreContextSlot(HStoreContextSlot* instr) {
+  Abort("Unimplemented: DoStoreContextSlot");
+  return NULL;
+}
+
+
 LInstruction* LChunkBuilder::DoLoadNamedField(HLoadNamedField* instr) {
   ASSERT(instr->representation().IsTagged());
   LOperand* obj = UseRegisterAtStart(instr->object());