Don't scale single-char text divs.

This change makes scrolling noticeably smoother on files with many
single-char text divs, such as the one in #1045. The trade-off is that
the visual appearance of text selection in such documents is slightly
worse, because more text divs overlap.

This change also uses `scaleX(N)` instead of `scale(N, 1)`. This might
be marginally more efficient in terms of JS string concatenation.
Remove a duplicate PDF file from the test suite

The files issue3115.pdf and issue2337.pdf are identical, the only difference being that the first one is an `eq` test and the second one a `load` test. Hence there is no reason to keep the `load` test, since it's just a subset of the `eq` test.
Fix handling of RGBA buffers in CalRGB colorspace (issue 5270)
Merge pull request #5276 from Snuffleupagus/issue-5270

Fix handling of RGBA buffers in CalRGB colorspace (issue 5270)
Merge pull request #5235 from Snuffleupagus/remove-duplicate-test-file

Remove a duplicate PDF file from the test suite
Merge pull request #5221 from nnethercote/dont-scale-single-char-text-divs

Don't scale single-char text divs.
Fix the exception propagation when rejecting workerReadyCapability

Currently when an exception is thrown, we try to reject `workerReadyCapability` with multiple arguments in src/core/api.js. This obviously doesn't work, hence this patch changes that to instead reject with the exception object as is.
In src/core/worker.js the exception is currently (unncessarily) wrapped in an object, so this patch also simplifies that to directly send the exception object instead.
Change `getDocumentError` in web/viewer.js to use `instanceof` instead of the exception name
In test/unit/api_spec.js rename the function `waitsForPromise` to `waitsForPromiseResolved`and add a `waitsForPromiseRejected` function
Add unit test for |MissingPDFException|