Reduce TokenDesc size by 20% on 64b platforms.

(40B -> 32B, due to alignment rules. Should be neutral on 32b platforms.)

BUG=v8:4947

Review-Url: https://codereview.chromium.org/2256183005
Cr-Commit-Position: refs/heads/master@{#38794}

src/parsing/scanner.h

@@ -495,11 +495,11 @@ class Scanner {
 
   // The current and look-ahead token.
   struct TokenDesc {
-    Token::Value token;
     Location location;
     LiteralBuffer* literal_chars;
     LiteralBuffer* raw_literal_chars;
     int smi_value_;
+    Token::Value token;
   };
 
   static const int kCharacterLookaheadBufferSize = 1;