This major version bump required two changes:
- The global line in the mobile viewer example should be removed because
the `.eslintrc` file already defines these globals and with the new
`eslint` version we otherwise get an error saying "'pdfjsLib' is already
defined as a built-in global variable".
- The ECMA version for the examples must be set to 6 since we're using
modules, otherwise we get an error saying "sourceType 'module' is not
supported when ecmaVersion < 2015". It turns out that the previous
version of `eslint` already used ECMA version 6 silently even though
we set 5, see https://github.com/eslint/eslint/issues/9687#issuecomment-432413384,
so in terms of our code nothing really changes.
Rather than having two different (but connected) options for the textLayer, I think that it makes sense to try and unify this. For example: currently if `disableTextLayer === true`, then the value of `enhanceTextSelection` is simply ignored.
Since PDF.js version `2.0` already won't be backwards compatible in lots of ways, I don't think that we need to worry about migrating existing preferences here.
This removes the `PDFJS.useOnlyCssZoom` dependency from the viewer components, but please note that as a *temporary* solution the default viewer still uses it.
Since the `mobile-viewer` example is based on the old FirefoxOS/B2G PDF viewer, it didn't need to have the same kind of `open/close` methods as the default viewer.
However, now that it has been re-purposed as a simple `mobile-viewer` example, it seems like a good idea to ensure that it has proper asynchronous `open/close` methods.
Fixes 7571.
