Handle single quotes in backend parser

Author: krasnotsvetov

resharper/resharper-unity/src/JsonNew/Psi/Parsing/JsonNewTreeBuilder.cs

@@ -180,6 +180,13 @@ private bool ParseJsonLiteral(int mark)
                 Done(mark, ElementType.JSON_NEW_LITERAL_EXPRESSION);
                 return true;
             }
+
+            if (GetTokenType() == JsonNewTokenNodeTypes.SINGLE_QUOTED_STRING)
+            {
+                Advance();
+                myBuilder.Error(mark, GetExpectedMessage("Double quoted string"));
+                return true;
+            }
 
             myBuilder.Drop(mark);