Reland r13275 and 13276 (Remove most uses of StringInputBuffer).

src/objects-inl.h

Index: src/objects-inl.h
diff --git a/src/objects-inl.h b/src/objects-inl.h
index 7772cfefe2d17a53da79042a890f88ab59c89449..89623bd02c131e0a8f0e14baf1df739e8c9c9fdc 100644
--- a/src/objects-inl.h
+++ b/src/objects-inl.h
@@ -2845,21 +2845,31 @@ String* ConsStringIteratorOp::ContinueOperation(int32_t* type_out,
 
 
 uint16_t StringCharacterStream::GetNext() {
-  ASSERT((buffer8_ == NULL && end_ == NULL) || buffer8_ < end_);
+  ASSERT(buffer8_ != NULL && end_ != NULL);
+  // Advance cursor if needed.
+  // TODO(dcarney): Ensure uses of the api call HasMore first and avoid this.
+  if (buffer8_ == end_) HasMore();
+  ASSERT(buffer8_ < end_);
   return is_one_byte_ ? *buffer8_++ : *buffer16_++;
 }
 
 
-StringCharacterStream::StringCharacterStream(
-    String* string, unsigned offset, ConsStringIteratorOp* op)
+StringCharacterStream::StringCharacterStream(String* string,
+                                             ConsStringIteratorOp* op,
+                                             unsigned offset)
   : is_one_byte_(false),
-    buffer8_(NULL),
-    end_(NULL),
     op_(op) {
-  op->Reset();
+  Reset(string, offset);
+}
+
+
+void StringCharacterStream::Reset(String* string, unsigned offset) {
+  op_->Reset();
+  buffer8_ = NULL;
+  end_ = NULL;
   int32_t type = string->map()->instance_type();
   unsigned length = string->length();
-  String::Visit(string, offset, *this, *op, type, length);
+  String::Visit(string, offset, *this, *op_, type, length);
 }