This card does not normally support OpenGL 2.0 fully, it just supports it partially, and there are some software replacements in the driver. Anyway, to enable it, on most Linux distributions you need to install driconf, and check two options as enabled:
1. Enable limited ARB_fragment_shader support on 915/945.
2. Enable stub ARB_occlusion_query support on 915/945.
To check if it worked, install mesa-demos and execute glxinfo or glxheads, it should say OpenGL 2.0 instead of 1.4 now. This will also make webgl work on the browsers, but you make experiente some problems with these options enabled, because as I said, this chipset does not seem to support OpenGL 2.0 fully.