Add pointer cache field to external string for access in generated code.

src/regexp-macro-assembler.cc

Index: src/regexp-macro-assembler.cc
diff --git a/src/regexp-macro-assembler.cc b/src/regexp-macro-assembler.cc
index f91ea9348f124a44f5f9d31bc868831f7299a526..99f3a37f4c8deaf7de4b1fb916ff85c1f89163f9 100644
--- a/src/regexp-macro-assembler.cc
+++ b/src/regexp-macro-assembler.cc
@@ -81,7 +81,7 @@ const byte* NativeRegExpMacroAssembler::StringCharacterPosition(
   if (subject->IsAsciiRepresentation()) {
     const byte* address;
     if (StringShape(subject).IsExternal()) {
-      const char* data = ExternalAsciiString::cast(subject)->resource()->data();
+      const char* data = ExternalAsciiString::cast(subject)->GetChars();
       address = reinterpret_cast<const byte*>(data);
     } else {
       ASSERT(subject->IsSeqAsciiString());
@@ -92,7 +92,7 @@ const byte* NativeRegExpMacroAssembler::StringCharacterPosition(
   }
   const uc16* data;
   if (StringShape(subject).IsExternal()) {
-    data = ExternalTwoByteString::cast(subject)->resource()->data();
+    data = ExternalTwoByteString::cast(subject)->GetChars();
   } else {
     ASSERT(subject->IsSeqTwoByteString());
     data = SeqTwoByteString::cast(subject)->GetChars();