WebGLContextAttributes类中的alpha depth stencil powerPreference
WebGLRenderingContextBase类中的VIEWPORT BOOL SAMPLER_CUBE
WebGL2RenderingContextBase类中的OBJECT_TYPE
WebGLRenderingContextBase类中的canvas
Signed-off-by: Nzleoyu <zhangleiyu1@huawei.com>
Change-Id: Id4b9bf353be581367717c7b4b57b003656f009b3