Add compositor support for half-float RGBA buffers and textures

gpu/command_buffer/service/gles2_cmd_decoder.cc

Index: gpu/command_buffer/service/gles2_cmd_decoder.cc
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder.cc b/gpu/command_buffer/service/gles2_cmd_decoder.cc
index 7234d1317adbedc9077af9dc3f625bb8477c14fe..ea7bace1dfcac53f2077e33258c9e50a65f2619f 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -3740,6 +3740,8 @@ Capabilities GLES2DecoderImpl::GetCapabilities() {
   caps.texture_rg = feature_info_->feature_flags().ext_texture_rg;
   caps.texture_half_float_linear =
       feature_info_->feature_flags().enable_texture_half_float_linear;
+  caps.color_buffer_float =
+      feature_info_->feature_flags().enable_color_buffer_float;
   caps.image_ycbcr_422 =
       feature_info_->feature_flags().chromium_image_ycbcr_422;
   caps.image_ycbcr_420v =