[interpreter] Move temporary register allocator into own file.

src/interpreter/bytecode-generator.h

Index: src/interpreter/bytecode-generator.h
diff --git a/src/interpreter/bytecode-generator.h b/src/interpreter/bytecode-generator.h
index bb96130460922305e675e3b9863f2dc03957d114..c4a3ce0ecad3483662e8cc44c4d2de8280623061 100644
--- a/src/interpreter/bytecode-generator.h
+++ b/src/interpreter/bytecode-generator.h
@@ -105,7 +105,8 @@ class BytecodeGenerator final : public AstVisitor {
   void RecordStoreToRegister(Register reg);
   Register LoadFromAliasedRegister(Register reg);
 
-  inline BytecodeArrayBuilder* builder() { return &builder_; }
+  inline void set_builder(BytecodeArrayBuilder* builder) { builder_ = builder; }
+  inline BytecodeArrayBuilder* builder() const { return builder_; }
 
   inline Isolate* isolate() const { return isolate_; }
   inline Zone* zone() const { return zone_; }
@@ -142,7 +143,7 @@ class BytecodeGenerator final : public AstVisitor {
 
   Isolate* isolate_;
   Zone* zone_;
-  BytecodeArrayBuilder builder_;
+  BytecodeArrayBuilder* builder_;
   CompilationInfo* info_;
   Scope* scope_;
   ZoneVector<Handle<Object>> globals_;