Support strikethrough text in Html.fromHtml().
Support strikethrough text in Html.fromHtml().

All the three tags, <del>, <s>, and <strike> are now converted to
strikethrough text.

Bug: 21025743
Change-Id: I62dc9793223e266f6e2181169766fde8be0e2aa7

xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base