Gardening: fast/text-autosizing/hackernews-comments.html fails

It was auto-rebaselined in Blink r173048 but still fails.
Marking as failure.

BUG=365911
TBR=pdr

Review URL: https://codereview.chromium.org/268633003

git-svn-id: svn://svn.chromium.org/blink/trunk@173063 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Add support for type checking of floating point attributes

Just do the same thing for value passed to setter(if (!std::isfinite) ...)
as for method arguments.

Add examples in SourceBuffer for checking.

Followup to:
Add support for type checking of floating point arguments as [TypeChecking=Unrestricted]
https://codereview.chromium.org/259773008/

This does *not* add TypeChecking throughout SourceBuffer, only enough for testing; Fredrik is doing full type checking in:
Apply TypeChecking to MediaSource IDLs
https://codereview.chromium.org/266453005/

R=haraken
BUG=354298
TEST=http/tests/media/media-source/mediasource-timestamp-offset.html
TEST=http/tests/media/media-source/mediasource-appendwindow.html

Review URL: https://codereview.chromium.org/265753003

git-svn-id: svn://svn.chromium.org/blink/trunk@173064 bbb929c8-8fbe-4397-9dbb-9b2b20218538