[interpreter] Add CreateFunctionContext bytecode

src/interpreter/bytecode-array-builder.cc

Index: src/interpreter/bytecode-array-builder.cc
diff --git a/src/interpreter/bytecode-array-builder.cc b/src/interpreter/bytecode-array-builder.cc
index b205c32b0f37010e21ad06d733269c338b136e82..352ef9dd8b95488e2822b5133d60a7b51a11d0e1 100644
--- a/src/interpreter/bytecode-array-builder.cc
+++ b/src/interpreter/bytecode-array-builder.cc
@@ -337,6 +337,11 @@ BytecodeArrayBuilder& BytecodeArrayBuilder::CreateClosure(
   return *this;
 }
 
+BytecodeArrayBuilder& BytecodeArrayBuilder::CreateFunctionContext(int slots) {
+  Output(Bytecode::kCreateFunctionContext, SignedOperand(slots));

[rmcilroy, 2016/08/03 10:58:14]

Signed? This should always be positive right? Could you make the bytecode take
an unsigned operand (we probably need to add a new type or rename the Idx type).
Feel free to do this in a followup CL and just add a TODO here

[klaasb, 2016/08/03 12:28:16]

Switched to unsigned and Idx in bytecodes.h, added a comment there.

+  return *this;
+}
+
 BytecodeArrayBuilder& BytecodeArrayBuilder::CreateArguments(
     CreateArgumentsType type) {
   // TODO(rmcilroy): Consider passing the type as a bytecode operand rather