Eliminate extended mode, and other modes clean-up

src/v8globals.h

Index: src/v8globals.h
diff --git a/src/v8globals.h b/src/v8globals.h
index 7d8d1b7e400794b7105314445d4bde0fad09ab29..2e0ead3a795661dfb4fa01a89eb1e3f6d240a4f2 100644
--- a/src/v8globals.h
+++ b/src/v8globals.h
@@ -465,11 +465,11 @@ enum VariableMode {
   // User declared variables:
   VAR,             // declared via 'var', and 'function' declarations
 
-  CONST,           // declared via 'const' declarations
+  CONST_LEGACY,    // declared via legacy 'const' declarations
 
   LET,             // declared via 'let' declarations (first lexical)
 
-  CONST_HARMONY,   // declared via 'const' declarations in harmony mode
+  CONST,           // declared via 'const' declarations
 
   MODULE,          // declared via 'module' declaration (last lexical)
 
@@ -510,7 +510,7 @@ inline bool IsLexicalVariableMode(VariableMode mode) {
 
 
 inline bool IsImmutableVariableMode(VariableMode mode) {
-  return mode == CONST || (mode >= CONST_HARMONY && mode <= MODULE);
+  return (mode >= CONST && mode <= MODULE) || mode == CONST_LEGACY;
 }