Remove CONST_LEGACY VariableMode

src/globals.h

Index: src/globals.h
diff --git a/src/globals.h b/src/globals.h
index 7aff576c6f4bd30dbbf1dd84dd9423cc85062d54..34f9fa693590f7eb57fa28e0eaffe33700950441 100644
--- a/src/globals.h
+++ b/src/globals.h
@@ -884,8 +884,6 @@ enum VariableMode {
   // User declared variables:
   VAR,  // declared via 'var', and 'function' declarations
 
-  CONST_LEGACY,  // declared via legacy 'const' declarations
-
   LET,  // declared via 'let' declarations (first lexical)
 
   CONST,  // declared via 'const' declarations (last lexical)
@@ -921,11 +919,6 @@ inline bool IsLexicalVariableMode(VariableMode mode) {
   return mode >= LET && mode <= CONST;
 }
 
-
-inline bool IsImmutableVariableMode(VariableMode mode) {
-  return mode == CONST || mode == CONST_LEGACY;
-}
-
 enum class VariableLocation {
   // Before and during variable allocation, a variable whose location is
   // not yet determined.  After allocation, a variable looked up as a