Adjusting how JS errors are tracked.
Adjusting how JS errors are tracked.

- Checking for a valid lineno instead of the filename to filter out
  "(0): Script error." logging
- Tracking stack traces separately from exceptions to make debugging
  easier

sunao0626/regexper-static,freddiecoleman/regexper-static,andrewhead/regexper-static,andrewhead/regexper-static,angrilove/regexper-static,freddiecoleman/regexper-static,javallone/regexper-static,sax1johno/regexper-static,stof/regexper-static,andrewhead/regexper-static,angrilove/regexper-static,javallone/regexper-static,ThibWeb/regexper-static,ThibWeb/regexper-static,sax1johno/regexper-static,sunao0626/regexper-static,stof/regexper-static,stof/regexper-static,angrilove/regexper-static,freddiecoleman/regexper-static,sax1johno/regexper-static,sunao0626/regexper-static