Add fill-opacity overlapping test-suite test

[lucaswoj]

ref mapbox/mapbox-gl-test-suite#117

[lucaswoj]

Blocked on merging this by some failing test-suite cases that have been added since the last GL JS sync

[lucaswoj]

Failing test cases:

• layout-property-function-to-default
• layout-property-function-to-literal
• layout-property-literal-to-default
• layout-property-literal-to-function
• paint-property-function-to-default

[jfirebaugh]

@lucaswoj Those are tests I added and I believe the failures are indications of bugs in gl-js. Do you want me to file tickets and disable them for now, or are you on the case?

[lucaswoj]

Disabling tests doesn't allow test-suite to pass in the case of runtime exceptions (this case). I'm going to make some changes to the test-suite harness and fix these bugs first thing tomorrow.

[jfirebaugh]

Disabling with "js": false (rather than "ignored": {...}) will prevent the test from running entirely.