[interpreter] Support for ES6 class literals.

src/interpreter/bytecodes.h

Index: src/interpreter/bytecodes.h
diff --git a/src/interpreter/bytecodes.h b/src/interpreter/bytecodes.h
index ecaa5166acd8b4eb483b384e5718745d6c391d59..968d6d7ae80f8dedecaaee2bcaba509eda7fabcb 100644
--- a/src/interpreter/bytecodes.h
+++ b/src/interpreter/bytecodes.h
@@ -142,6 +142,9 @@ namespace interpreter {
   V(KeyedStoreICStrictWide, OperandType::kReg8, OperandType::kReg8,            \
     OperandType::kIdx16)                                                       \
                                                                                \
+  /* Class information */                                                      \
+  V(LdaInitialMap, OperandType::kNone)                                         \
+                                                                               \
   /* Binary Operators */                                                       \
   V(Add, OperandType::kReg8)                                                   \
   V(Sub, OperandType::kReg8)                                                   \
@@ -307,10 +310,7 @@ class Register {
  public:
   explicit Register(int index = kInvalidIndex) : index_(index) {}
 
-  int index() const {
-    DCHECK(index_ != kInvalidIndex);
-    return index_;
-  }
+  int index() const { return index_; }
   bool is_parameter() const { return index() < 0; }
   bool is_valid() const { return index_ != kInvalidIndex; }
   bool is_byte_operand() const;