Revert "fix test issue"

This reverts commit d26fc97acdfb512c8f9b1bbe5edc2cd9cd4d55c2.

engine/src/shell/platform/unity/unity_surface_manager.cc

 
   FML_DCHECK(fbo_texture_ == 0);
   glGenTextures(1, &fbo_texture_);
-
-  GLint oldId;
-  glGetIntegerv(GL_TEXTURE_BINDING_2D, &oldId);
-
   glBindTexture(GL_TEXTURE_2D, fbo_texture_);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
-
- glBindTexture(GL_TEXTURE_2D, oldId);
 
   FML_DCHECK(fbo_ == 0);
   glGenFramebuffers(1, &fbo_);