There's no dirty bit handler if VK_EXT_transform_feedback disabled, but
we're setting that dirty bit in syncState. This results in calling a null
method pointer. Skip the invalidate if the extension is not enabled.

    gl::LogMessage::~LogMessage() at ./../../third_party/angle/src/common/debug.cpp:0
    rx::ContextVk::setupDraw(gl::Context const*, gl::PrimitiveMode, int, int, int, gl::DrawElementsType, void const*, angle::BitSetT<11ul, unsigned long, unsigned long>, rx::vk::priv::SecondaryCommandBuffer**) at ./../../third_party/angle/src/libANGLE/renderer/vulkan/ContextVk.cpp:844
    rx::ContextVk::drawArrays(gl::Context const*, gl::PrimitiveMode, int, int) at ./../../third_party/angle/src/libANGLE/renderer/vulkan/ContextVk.cpp:1698
    gl::Context::drawArrays(gl::PrimitiveMode, int, int) at ./../../third_party/angle/src/libANGLE/Context.inl.h:112
    gl::DrawArrays(unsigned int, int, int) at ./../../third_party/angle/src/libGLESv2/entry_points_gles_2_0_autogen.cpp:926
    (anonymous namespace)::AttributeLayoutNonIndexed::Draw(int, unsigned int, unsigned short const*) at ./../../third_party/angle/src/tests/gl_tests/AttributeLayoutTest.cpp:431
    (anonymous namespace)::AttributeLayoutTest::Run(bool) at ./../../third_party/angle/src/tests/gl_tests/AttributeLayoutTest.cpp:305

[This stack is from the added assert; calling a null function pointer
crashes without producing a useful stack trace.]

Bug: angleproject:4326
Change-Id: I036ae322bddc4865229fa3fe7ea72a4344b99f83
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2011408
Commit-Queue: Michael Spang <spang@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>