fix: per-context WebGL overrides when launch parameters are set

[PopcornDev1]

Summary

Fixes a WebGL spoofing precedence issue where launch-level webGl:parameters
entries for UNMASKED_VENDOR_WEBGL and UNMASKED_RENDERER_WEBGL could override
per-context WebGL vendor/renderer values.

The affected WebGL constants are:

• 37445 / UNMASKED_VENDOR_WEBGL
• 37446 / UNMASKED_RENDERER_WEBGL

Previously, ClientWebGLContext::GetParameter() checked the generic
MaskConfig::GLParam() path before the existing per-context
WebGLParamsManager path. If the launch fingerprint included
webGl:parameters["37445"] or webGl:parameters["37446"], those global values
won even when a context had its own WebGL vendor/renderer configured.

This change skips the generic parameter lookup for those two debug-renderer
constants so the existing order is preserved:

1. Require WEBGL_debug_renderer_info to be enabled.
2. Use per-context WebGL vendor/renderer when present.
3. Fall back to global webGl:vendor / webGl:renderer.

Testing

• Separate contexts can report separate WebGL vendor/renderer values.
• Per-context WebGL overrides launch-level webGl:vendor / webGl:renderer.
• Per-context WebGL overrides launch-level webGl:parameters["37445"] /
  ["37446"].
• NewContext presets apply WebGL vendor/renderer values.

Verified locally against a rebuilt Camoufox binary:

tests/patches/live-webgl-
context.py::test_context_webgl_vendor_renderer_are_isolated_and_reusable PASSED
tests/patches/live-webgl-
context.py::test_context_webgl_overrides_launch_config_webgl PASSED
tests/patches/live-webgl-
context.py::test_context_webgl_overrides_launch_parameter_webgl PASSED
tests/patches/live-webgl-
context.py::test_new_context_applies_preset_webgl_vendor_renderer PASSED

4 passed

Also verified manually with CreepJS:

• CreepJS saw the context-specific WebGL vendor/renderer.
• CreepJS did not show the conflicting parent/global launch values.
• Two separate contexts reported separate WebGL GPU identities.

• Validated with VulpineOS against a rebuilt local Camoufox binary to cover the browser-agent runtime case: multiple isolated contexts in one launched browser process, each with its own WebGL vendor/renderer. CreepJS observed the context-specific GPU values and did not show the conflicting launch-level webGl:parameters["37445"] / ["37446"] values.

[PopcornDev1]

@icepaq