Revert of Internalize strings in-place

include/v8.h

Index: include/v8.h
diff --git a/include/v8.h b/include/v8.h
index eb5d00afb220a7eab39b6e5e9f4a3a5233b30520..822b6a56656310d56d491d1c2af032c118d6844e 100644
--- a/include/v8.h
+++ b/include/v8.h
@@ -2313,7 +2313,7 @@ class V8_EXPORT String : public Name {
   enum Encoding {
     UNKNOWN_ENCODING = 0x1,
     TWO_BYTE_ENCODING = 0x0,
-    ONE_BYTE_ENCODING = 0x8
+    ONE_BYTE_ENCODING = 0x4
   };
   /**
    * Returns the number of characters in this string.
@@ -8437,10 +8437,10 @@ class Internals {
   static const int kFixedArrayHeaderSize = 2 * kApiPointerSize;
   static const int kContextHeaderSize = 2 * kApiPointerSize;
   static const int kContextEmbedderDataIndex = 5;
-  static const int kFullStringRepresentationMask = 0x0f;
-  static const int kStringEncodingMask = 0x8;
+  static const int kFullStringRepresentationMask = 0x07;
+  static const int kStringEncodingMask = 0x4;
   static const int kExternalTwoByteRepresentationTag = 0x02;
-  static const int kExternalOneByteRepresentationTag = 0x0a;
+  static const int kExternalOneByteRepresentationTag = 0x06;
 
   static const int kIsolateEmbedderDataOffset = 0 * kApiPointerSize;
   static const int kExternalMemoryOffset = 4 * kApiPointerSize;