Allow depth and depth-stencil formats and types for textures and update utility functions Trac #20875 Signed-off-by: Nicolas Capens TexImage2D accepts format,internalformat=DEPTH_COMPONENT, type=UNSIGNED_SHORT format,internalformat=DEPTH_COMPONENT, type=UNSIGNED_INT format,internalformat=DEPTH_STENCIL_OES, type=UNSIGNED_INT_24_8_OES TexSubImage2D accepts format=DEPTH_COMPONENT, type=UNSIGNED_SHORT format=DEPTH_COMPONENT, type=UNSIGNED_INT format=DEPTH_STENCIL_OES, type=UNSIGNED_INT_24_8_OES TexStorage2DEXT accepts internalformat=DEPTH_COMPONENT16 internalformat=DEPTH_COMPONENT32_OES internalformat=DEPTH24_STENCIL8_OES git-svn-id: https://angleproject.googlecode.com/svn/trunk@1104 736b8ea6-26fd-11df-bfd4-992fa37f6226