Split incremental marking write barrier into fast and slow paths.

src/scanner.h

Index: src/scanner.h
diff --git a/src/scanner.h b/src/scanner.h
index a2e64a9d2000125a05167034f41026881bc44988..6e689b606a0beee8fff3058b9b83535609eabed0 100644
--- a/src/scanner.h
+++ b/src/scanner.h
@@ -169,7 +169,7 @@ class LiteralBuffer {
     }
   }
 
-  inline void AddChar(uc16 character) {
+  INLINE(void AddChar(uc16 character)) {
     if (position_ >= backing_store_.length()) ExpandBuffer();
     if (is_ascii_) {
       if (character < kMaxAsciiCharCodeU) {
@@ -389,7 +389,7 @@ class Scanner {
     next_.literal_chars = free_buffer;
   }
 
-  inline void AddLiteralChar(uc32 c) {
+  INLINE(void AddLiteralChar(uc32 c)) {
     ASSERT_NOT_NULL(next_.literal_chars);
     next_.literal_chars->AddChar(c);
   }