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: I8feaa69b93c263907401bf338bd5c6643186fb7e