Add support for GL_OES_fbo_render_mipmap with OpenGL.

src/libANGLE/renderer/gl/renderergl_utils.cpp

@@ -187,6 +187,7 @@ void GenerateCaps(const FunctionsGL *functions, gl::Caps *caps, gl::TextureCapsM
     extensions->setTextureExtensionSupport(*textureCapsMap);
     extensions->textureNPOT = true;
     extensions->textureStorage = true;
+    extensions->fboRenderMipmap = true;
 }
 
 }

src/tests/end2end_tests/FramebufferRenderMipmapTest.cpp

 #include "ANGLETest.h"
 
 // Use this to select which configurations (e.g. which renderer, which GLES major version) these tests should be run against.
-ANGLE_TYPED_TEST_CASE(FramebufferRenderMipmapTest, ES2_D3D9, ES2_D3D11, ES3_D3D11);
+ANGLE_TYPED_TEST_CASE(FramebufferRenderMipmapTest, ES2_D3D9, ES2_D3D11, ES3_D3D11, ES2_OPENGL, ES3_OPENGL);
 
 template<typename T>
 class FramebufferRenderMipmapTest : public ANGLETest