Add support to CHROMIUM_color_buffer_rgba for creating RGBA32F renderbuffers on ES2. This is desired for implementing WEBGL_color_buffer_float support on WebGL1 on ANGLE's ES2 driver, for Firefox. Bug: angleproject:3322 Change-Id: I599f86db62402333d3ef9235956c63e667f1513d Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1541722 Reviewed-by: Kenneth Russell <kbr@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org> Commit-Queue: Kenneth Russell <kbr@chromium.org>