[Interpreter] Add support for loading globals in the interpreter.

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 f3a1b1ea0803959990370da458ae10da87d8ec54..2d06765cd1cb1e12592f9cb8a213e63ea0ef8619 100644
--- a/src/interpreter/bytecode-array-builder.cc
+++ b/src/interpreter/bytecode-array-builder.cc
@@ -152,6 +152,16 @@ BytecodeArrayBuilder& BytecodeArrayBuilder::StoreAccumulatorInRegister(
 }
 
 
+BytecodeArrayBuilder& BytecodeArrayBuilder::LoadGlobal(int slot_index) {
+  DCHECK(slot_index >= 0);
+  if (FitsInByteOperand(slot_index)) {
+    Output(Bytecode::kLdaGlobal, static_cast<uint8_t>(slot_index));
+  } else {
+    UNIMPLEMENTED();
+  }
+  return *this;
+}
+
 BytecodeArrayBuilder& BytecodeArrayBuilder::LoadNamedProperty(
     Register object, int feedback_slot, LanguageMode language_mode) {
   if (!is_sloppy(language_mode)) {