GL: fix test asserts with the recently-deprecated nullptr ImageView.

src/Magnum/GL/Test/FramebufferGLTest.cpp

@@ -1599,7 +1599,7 @@ void FramebufferGLTest::readViewNullptr() {
     Framebuffer framebuffer({{}, Vector2i(128)});
     framebuffer.attachRenderbuffer(Framebuffer::ColorAttachment(0), color);
 
-    MutableImageView2D view{DataStorage, PixelFormat::RGBA, PixelType::UnsignedByte, {8, 16}, {nullptr, (DataOffset + 8*15)*sizeof(Color4ub)}};
+    MutableImageView2D view{DataStorage, PixelFormat::RGBA, PixelType::UnsignedByte, {8, 16}};
 
     std::ostringstream out;
     Error redirectError{&out};

src/Magnum/GL/Test/TextureGLTest.cpp

@@ -2902,7 +2902,7 @@ void TextureGLTest::srgbStorage() {
         #else
         PixelFormat::SRGB
         #endif
-        , PixelType::UnsignedByte, Vector2i{32}, nullptr});
+        , PixelType::UnsignedByte, Vector2i{32}, {nullptr, 32*32*3}});
 
     MAGNUM_VERIFY_NO_GL_ERROR();
 
@@ -2936,7 +2936,7 @@ void TextureGLTest::srgbAlphaStorage() {
         #else
         PixelFormat::SRGBAlpha
         #endif
-        , PixelType::UnsignedByte, Vector2i{32}, nullptr});
+        , PixelType::UnsignedByte, Vector2i{32}, {nullptr, 32*32*4}});
 
     MAGNUM_VERIFY_NO_GL_ERROR();