Remove empty TextNode left behind by IE8 setInnerHTML workaround

[syranide]

What the title says, if it appends the \uFEFF to fix whitespace it can end up leaving an empty TextNode behind. This is very bad because it offsets the index of children. Also, renderComponent still uses firstChild which causes it to see the TextNode and replace the content rather than update it as it should.

@zpao We definitely want to merge this sooner rather than later.

[syranide]

@zpao I've added a simple test-case to prevent future regressions (but like spicyj said, we don't run these tests on IE8?).

[zpao]

Is .removeNode universally supported? If not, node.removeChild(textNode) is definitely safe.
— @benjamn

[zpao]

Looks like it's only IE (and I don't know what versions). This workaround is only IE though so that might be ok. any chance this will ever run for non-IE?

[syranide]

@zpao My intention here was that this only targets IE8, which does support it. As I mentioned somewhere else, we could change the feature test to just document.documentMode === 8, because if some other old browser flunks the test, I really doubt that this trickery would fix it.

[syranide]

Change pushed.

[syranide]

@zpao For posterity, this was actually a sneaky side-effect of #1495 (and not an issue with the initial fix). Before that, the TextNode could never be a single char (the prefix char) as there had to be white-space after it.