Preparser extracted into separate files that can be compiled to a library.

src/scanner-base.h

Index: src/scanner-base.h
diff --git a/src/scanner-base.h b/src/scanner-base.h
index 3714ae2d1bc626ad2a2127b3fe5dcc6b86cef84b..3d344f306ca0953e479ee90fe5446e0b999243f3 100644
--- a/src/scanner-base.h
+++ b/src/scanner-base.h
@@ -228,8 +228,6 @@ class Scanner {
     return Vector<const char>(next_literal_string(), next_literal_length());
   }
 
-  bool stack_overflow() { return stack_overflow_; }
-
   static const int kCharacterLookaheadBufferSize = 1;
 
  protected:
@@ -316,8 +314,6 @@ class Scanner {
   // using '\x00'-terminated UTF-8 encoding. Handles allocation internally.
   LiteralCollector literal_buffer_;
 
-  bool stack_overflow_;
-
   // One Unicode character look-ahead; c0_ < 0 at the end of the input.
   uc32 c0_;
 };