MQE-1117: dontSeeJsError does not catch JS errors

[jilu1]

Description

MQE-1117: dontSeeJsError does not catch JS errors

Contribution checklist

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/verification tests (if applicable)
• All automated tests passed successfully (all builds on Travis CI are green)
• Changes to Framework doesn't have backward incompatible changes for tests or have related Pull Request with fixes to tests

[coveralls]

Coverage decreased (-0.008%) to 57.151% when pulling a10efc5 on MQE-1117 into 31ddcc8 on develop.

[coveralls]

Coverage remained the same at 57.516% when pulling 95e0b23 on MQE-1117 into 94afc74 on develop.

[KevinBKozan]

Spoke in person, we should clear the cache of JS errors on a per-page basis; the cache needs some context, otherwise an error could occur in the very beggining of the test, and calling dontSeeJSError at the very end would cause a failure.

[KevinBKozan]

Changes look good to me, feature works as expected.
Make sure that:

1. Devdocs points out that dontseejserror is per-page
2. Fix static errors