Fix attribute-dropped warning.

<br title/ > is part of a parserTest; we do the right thing in that
case (that is, we ignore the bogus attribute, which is correct for
wt2html at least).

But don't dump text to console.log when the html5 parse algorithm is Doing
The Right Thing.  You can enable this with HTML5.enableDebug() if needed.

Change-Id: I2a585a9f882aaf845b11f96bf30def03c2739414
Merge "Fix attribute-dropped warning."