lookChar refactoring
Limit image size to 1024*1024 for b2g.
Always declare window.URL even if undefined

Otherwise it breaks feature detection,
"ReferenceError: Can't find variabl: URL" in Safari 5.1
Merge pull request #3459 from Rob--W/define-URL

Always declare window.URL even if undefined
Merge pull request #3424 from yurydelendik/lookChar

lookChar refactoring
Merge pull request #3456 from brendandahl/cap-image-size

Limit image size to 1024*1024 for b2g.
Refactoring download button logic
Rejects incorrect url in download manager
Merge pull request #3467 from yurydelendik/download-refactor

Refactor download logic
Restoring PR 3455 functionality
Merge pull request #3468 from yurydelendik/download-refactor

Restoring PR 3455 functionality
Merge branch 'master' of github.com:mozilla/pdf.js into incremental-rendering2

Conflicts:
	src/annotation.js
	src/evaluator.js