Return MaybeHandle from NewRaw???String.

src/json-parser.h

Index: src/json-parser.h
diff --git a/src/json-parser.h b/src/json-parser.h
index 4c2b479182db68654866d2fbb128dff6987548ed..ca21421d44838ccdd4e23771d9da4679f51483d6 100644
--- a/src/json-parser.h
+++ b/src/json-parser.h
@@ -583,14 +583,14 @@ template <>
 inline Handle<SeqTwoByteString> NewRawString(Factory* factory,
                                              int length,
                                              PretenureFlag pretenure) {
-  return factory->NewRawTwoByteString(length, pretenure);
+  return factory->NewRawTwoByteString(length, pretenure).ToHandleChecked();
 }
 
 template <>
 inline Handle<SeqOneByteString> NewRawString(Factory* factory,
                                            int length,
                                            PretenureFlag pretenure) {
-  return factory->NewRawOneByteString(length, pretenure);
+  return factory->NewRawOneByteString(length, pretenure).ToHandleChecked();
 }
 
 
@@ -606,7 +606,6 @@ Handle<String> JsonParser<seq_ascii>::SlowScanJsonString(
   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);
@@ -793,8 +792,8 @@ Handle<String> JsonParser<seq_ascii>::ScanJsonString() {
     }
   } while (c0_ != '"');
   int length = position_ - beg_pos;
-  Handle<String> result = factory()->NewRawOneByteString(length, pretenure_);
-  ASSERT(!result.is_null());
+  Handle<String> result =
+      factory()->NewRawOneByteString(length, pretenure_).ToHandleChecked();
   uint8_t* dest = SeqOneByteString::cast(*result)->GetChars();
   String::WriteToFlat(*source_, dest, beg_pos, position_);