Respond to Ivan's code review comments from previous TBR cl.

runtime/vm/object.cc

Index: runtime/vm/object.cc
diff --git a/runtime/vm/object.cc b/runtime/vm/object.cc
index 74249daeee3284148df1db7dddc810c87b5a74bd..c961366b4233445e0465a2406a8f1263be9c3754 100644
--- a/runtime/vm/object.cc
+++ b/runtime/vm/object.cc
@@ -13680,7 +13680,7 @@ RawOneByteString* OneByteString::EscapeSpecialCharacters(const String& str) {
     }
     return OneByteString::raw(dststr);
   }
-  return OneByteString::New(static_cast<intptr_t>(0), Heap::kNew);
+  return OneByteString::raw(Symbols::Empty());
 }
 
 RawOneByteString* ExternalOneByteString::EscapeSpecialCharacters(
@@ -13709,7 +13709,7 @@ RawOneByteString* ExternalOneByteString::EscapeSpecialCharacters(
     }
     return OneByteString::raw(dststr);
   }
-  return OneByteString::New(static_cast<intptr_t>(0), Heap::kNew);
+  return OneByteString::raw(Symbols::Empty());
 }
 
 
@@ -13906,7 +13906,7 @@ RawTwoByteString* TwoByteString::EscapeSpecialCharacters(const String& str) {
     }
     return TwoByteString::raw(dststr);
   }
-  return TwoByteString::New(0, Heap::kNew);
+  return TwoByteString::raw(Symbols::Empty());

[Ivan Posva, 2013/10/01 03:14:22]

Actually this is incorrect as Symbols::Empty is a OneByteString. We should fix
the implementation of TwoByteString.

[Jacob, 2013/10/01 17:25:26]

Switched this one back to calling
TwoByteString::New(0, Heap::kNew); 

 }