Mark last render target bound ID invalid after clearing texture levels using glClear

Fixes WebGL invalid framebuffer issues.

Change-Id: I841b8aa27f126feeb9971123c8b025630cdd3e0b
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/241757
Commit-Queue: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Auto-Submit: Brian Salomon <bsalomon@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>

src/gpu/gl/GrGLGpu.cpp

@@ -1298,6 +1298,7 @@ sk_sp<GrTexture> GrGLGpu::onCreateTexture(const GrSurfaceDesc& desc,
                     this->unbindSurfaceFBOForPixelOps(tex.get(), i, GR_GL_FRAMEBUFFER);
                 }
             }
+            fHWBoundRenderTargetUniqueID.makeInvalid();
         } else {
             std::unique_ptr<char[]> zeros;
             GL_CALL(PixelStorei(GR_GL_UNPACK_ALIGNMENT, 1));