Bug 1683936 - Disable persistently mapped buffers on Adreno devices. r=sotaro
Bug 1683936 - Disable persistently mapped buffers on Adreno devices. r=sotaro

There is a driver bug on old versions of the Adreno driver which
prevents usage of persistenly mapped buffers for texture
uploads. Creating and mapping the buffer works correctly, but
attempting to upload to a texture from the buffer results in an error
due to the buffer still being mapped.

This means that no texture data is uploaded, essentially meaning that
we do not render anything at all.

It appears to affect at least Adreno 4xx and 5xx devices running
Android 6. For now, simply disable persistent mapping on all Adreno
devices, until we know more specifically which are affected.

Differential Revision: https://phabricator.services.mozilla.com/D100391

[ghsync] From https://hg.mozilla.org/mozilla-central/rev/1de3ccd3da570e852f14b86c21ff7a3fb5c82c75

servo/webrender,servo/webrender,servo/webrender,servo/webrender,servo/webrender,servo/webrender