Add a few debug asserts to GFX frame building code

Turns iloops into quick aborts in the case where we try to add a frame as its own child. Yes, this happened to me.
Fix error message for exception in EventDispatcher#dispatchEvent
Bug 1066566 - Re-enable loading initial SWF from an ArrayBuffer

This broke in the nat refactoring
Bug 1066566 - Fix the "Open File" button in the Inspector
Merge pull request #1707 from tschneidereit/master

[Bug 1066566] Fix inspector's "Open File" functionality
Hack to wait for Chrome to load fonts
Merge pull request #1708 from yurydelendik/chromefont

Hack to wait for Chrome to load fonts
Ref images viewer
Warn about dropped tags in defineSymbol parsing

Turns out we silently swallow nested symbols, which we would've found out much earlier with such a warning.
Merge pull request #1715 from tschneidereit/parser

Warn about dropped tags in defineSymbol parsing