Sharing GLTextures between WebGL and Layers is possible with OGL Layers, available on Mac and Linux. (though heavily blacklisted on Linux)
Sharing EGLSurfaces provides the same functionality between ANGLE EGL+GLES and D3D10 Layers.
A more complete description of the backend combinations is at [[Platform/GfxGFX/WebGLBackendsWebGL/Backends]].
Currently, we lack composition acceleration on WinXP, most Linux, and Mobile.