Fix issue #2538228: Intents targeting browsers constantly nagging

Some applications are setting the MIME type field for an http:
intent, which is technically wrong because the recipient opening
the URI will get the MIME type from the header.  This was hitting
a bug when we compute the intent filter when setting the
preferred activity, where we have to set both the MIME type and
data URI for the intent filter.  (For file: and content: URIs
only the MIME type is needed, since these can be opened directly
through ContentResolver so everyone is presumed to be able to
handle them.)

Change-Id: Ia7025e6859e9c90997bf56c2c80f225fca7a2007