Does Firefox support hardware acceleration on Ubuntu?

After I have installed Ubuntu 12.04 LTS (32 bits), Firefox 12 works fine but without hardware acceleration. Needless to say I have the latest nVidia's proprietary drivers installed and my Firefox Preferences, on "Advanced" tab, "Browsing" section, have the option "Use hardware acceleration when available" checked.

I have tried the following things before asking this question:

• Creating a boolean key "webgl.force-enabled" and set it to true on Firefox's page about:config;

• Starting a new profile like commented on thread Mozilla Firefox 12 is very slow on Ubuntu 12.04 LTS;

• I have updated my nVidia driver to version 295.53.

And none of this have worked. As you can see below in my Firefox's page about:support report, "Graphics" section shows no "GPU Accelerated Windows":

Adapter Description     NVIDIA Corporation -- GeForce GTX 460/PCIe/SSE2
Vendor ID               NVIDIA Corporation
Device ID               GeForce GTX 460/PCIe/SSE2
Driver Version          4.2.0 NVIDIA 295.53
WebGL Renderer          NVIDIA Corporation -- GeForce GTX 460/PCIe/SSE2 -- 4.2.0 NVIDIA 295.53
GPU Accelerated Windows 0
AzureBackend            skia

I use the following site to test hardware acceleration:

http://ie.microsoft.com/testdrive/Performance/FishBowl/

On Windows 7 I get 60 fps even with 1,750 fishes on browser's Full Screen Mode (1680x1050x32bit-color). On Ubuntu 12.04 LTS, same nVidia drivers (as shown in report), won't go faster than 15 fps with only 1,000 fishes.

Can anybody help me?

My Firefox's page about:config, and this is showed in graphic details.

Adapter Description       ATI Technologies Inc. -- ATI Mobility Radeon HD 5000 Series 
Vendor ID                 ATI Technologies Inc.
Device ID                 ATI Mobility Radeon HD 5000 Series 
Driver Version            4.2.11627 Compatibility Profile Context
WebGL Renderer            ATI Technologies Inc. -- ATI Mobility Radeon HD 5000 Series  -- 4.2.11627 Compatibility Profile Context
GPU Accelerated Windows   0
AzureBackend              skia

It seems the browser can detect my GPU perfectly fine just it won't use it. This issue effects both NVIDIA and AMD user.

Currently, it's impossible for Firefox to use GPU on Linux. It's discussed at Ubuntu Forums.