Fix SourceBuffer.remove() calls for IE11
Fix SourceBuffer.remove() calls for IE11

On IE11, SourceBuffer.remove(start, Number.POSITIVE_INFINITY) triggers
an 'updateend' event, but does not seem to remove anything.  The same
is true if we swap Number.MAX_VALUE for Number.POSITIVE_INFINITY.
MediaSource.duration does seem to work, though, to remove all content
from buffer.

Fixes #251

Change-Id: I67152f8deceb8926ae1376fdccf73db0c62d0a3e

ustudio/shaka-player,shaka-project/shaka-player,TobbeEdgeware/shaka-player,cmgrecu/shaka-player,sanbornhnewyyz/shaka-player,TobbeEdgeware/shaka-player,tvoli/shaka-player,Ross-cz/shaka-player,russitto/shaka-player,cmgrecu/shaka-player,brightcove/shaka-player,samdutton/shaka-player,shaka-project/shaka-player,shaka-project/shaka-player,TheModMaker/shaka-player,indiereign/shaka-player,samdutton/shaka-player,Ross-cz/shaka-player,brightcove/shaka-player,shaka-project/shaka-player,indiereign/shaka-player,indiereign/shaka-player,tvoli/shaka-player,samdutton/shaka-player,sanbornhnewyyz/shaka-player,TheModMaker/shaka-player,TheModMaker/shaka-player,vimond/shaka-player,TobbeEdgeware/shaka-player,Ross-cz/shaka-player,tvoli/shaka-player,ustudio/shaka-player,TheModMaker/shaka-player,samdutton/shaka-player,vimond/shaka-player,ustudio/shaka-player,sanbornhnewyyz/shaka-player,baconz/shaka-player,vimond/shaka-player,sanbornhnewyyz/shaka-player,ustudio/shaka-player,tvoli/shaka-player,russitto/shaka-player,russitto/shaka-player,baconz/shaka-player,baconz/shaka-player,cmgrecu/shaka-player,brightcove/shaka-player