TextLayer selection coloring improvement for overlap.

As a consequence of merging #5221 it is more likely to have multiple
overlapping selection divs inside the text layer. Because each individual
element gets the selection style applied, the 30%opacity stacks, making a
60% bar visible where the overlap happens.

As proposed by @rocallahan, this can be fixed by making the selection
style solid and setting opacity for the overall layer.

I assume also that this should make the work for the renderer easier, but
was unable to bench it.
Fix Symbol fonts without font file but with Encoding dictionary (issue 5238)
Add support for MMType1 fonts with embedded font files
Fixes names collisions in content.js
textLayer is not used anymore in render context.

It should be removed to prevent confusion when reading the code.
Implement streaming using moz-chunk-arraybuffer
Replaces (chunk in this.loadedChunks)
Fixes milestones link in README.md
Adds pdfBugEnabled to the Chrome extension preferences
Merge pull request #5321 from timvandermeij/misc-fixes

Fixes milestones link in README.md and adds pdfBugEnabled to the Chrome extension preferences
Merge pull request #5318 from mitar/patch-2

textLayer is not used anymore in render context
Imports L10n
Builds distribution package for npm and bower.
Improve the getData unit test

As a follow-up to PR #4795, this patch improves the `getData` unit test to ensure that the returned data is of the expected type and of the correct length.
Merge pull request #5327 from yurydelendik/dist

Builds distribution package for npm and bower.
Merge pull request #5330 from Snuffleupagus/better-getData-unittest

Improve the getData unit test
Merge pull request #5314 from yurydelendik/issue5313

Fixes names collisions in content.js
Merge pull request #5282 from CodingFabian/nicer-overlapping-text-selection

TextLayer selection coloring improvement for overlap.
Fix text highlighting in the Font Inspector in the debugger

After PR #5282, the text highlighting in the Font Inspector is very hard to see against a white background. That seems to be an oversight from the mentioned PR, hence this patch fixes that.
Fix a regression preventing page change in the Stepper in the debugger

This is a regression from https://github.com/mozilla/pdf.js/commit/ddd3c8fc2fe7b8715bed6d6f146c206d133b5dd6, which prevents changing pages in the Stepper.

(Apart from fixing the bug, for the sake of consistency, I also removed one instance of `parseInt`.)