Revert "No longer OOM on invalid string length."

src/json-parser.h

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 588 matching lines @@
 // sequential string of type StringType.
 template <bool seq_ascii>
 template <typename StringType, typename SinkChar>
 Handle<String> JsonParser<seq_ascii>::SlowScanJsonString(
     Handle<String> prefix, int start, int end) {
   int count = end - start;
   int max_length = count + source_length_ - position_;
   int length = Min(max_length, Max(kInitialSpecialStringLength, 2 * count));
   Handle<StringType> seq_string =
       NewRawString<StringType>(factory(), length, pretenure_);
-  ASSERT(!seq_string.is_null());
   // Copy prefix into seq_str.
   SinkChar* dest = seq_string->GetChars();
   String::WriteToFlat(*prefix, dest, start, end);
 
   while (c0_ != '"') {
     // Check for control character (0x00-0x1f) or unterminated string (<0).
     if (c0_ < 0x20) return Handle<String>::null();
     if (count >= length) {
       // We need to create a longer sequential string for the result.
       return SlowScanJsonString<StringType, SinkChar>(seq_string, 0, count);
@@ skipping 167 matching lines @@
                                                           position_);
       }
     } else {
       return SlowScanJsonString<SeqOneByteString, uint8_t>(source_,
                                                            beg_pos,
                                                            position_);
     }
   } while (c0_ != '"');
   int length = position_ - beg_pos;
   Handle<String> result = factory()->NewRawOneByteString(length, pretenure_);
-  ASSERT(!result.is_null());
   uint8_t* dest = SeqOneByteString::cast(*result)->GetChars();
   String::WriteToFlat(*source_, dest, beg_pos, position_);
 
   ASSERT_EQ('"', c0_);
   // Advance past the last '"'.
   AdvanceSkipWhitespace();
   return result;
 }
 
 } }  // namespace v8::internal
 
 #endif  // V8_JSON_PARSER_H_