WebView-specific iframe_loader strategy

[danielweck]

Pre-process HTML on the fly (as the binary stream is pulled from the EPUB zipped archive, via the HTTP byte stream request) to inject the Javascript epubReadingSystem "bootstrapper" and MathJAX html>head>script

https://github.com/readium/readium-shared-js/blob/develop/js/views/iframe_loader.js#L179

This would negate the need for binary Blob URI iframe@src, thereby
allowing us to skip html>head>base@href and xml:base ...and as a byproduct: regain full SVG support, see:
readium/readium-shared-js#90

Note that the "cloud reader" configuration would continue using the Blob URI mechanism introduced by:
readium/readium-shared-js#76
..and the Chrome extension/app would use a similar pre-processing workflow to achieve the desired result:
readium/readium-js-viewer#142

Email discussion:
https://groups.google.com/forum/#!msg/readium-dev/MtLL2xe4bcQ/ItUynlrqL-0J

[danielweck]

PS: should this be in RD Services? Probably, but right now only SDKLauncher-iOS makes use of this shared backend framework.

[danielweck]

Addressed in this feature branch:

https://github.com/readium/SDKLauncher-OSX/commits/feature/htmlInject

[danielweck]

Now in Pull Request: #14