Reland "Check FP16 support on vulkan backend"

This reverts commit 0357eed7de15e901d14f6149e91bfe03d86958de
and reland commit bdc05c3d5fef780382c3fd5e5ebcb14bd929819a.

The Vulkan-Loader has a bug where if the instance is created
with Vulkan 1.1 and not the promoted extensions, it will skip
emulation and if the ICD doesn't support Vulkan 1.1 nor the
extensions. Enable the promoted extensions, even when creating
a Vulkan 1.1 instance.

Original change's description:
> Check FP16 support on vulkan backend
>
> This patch check FP16 support on vulkan backend, and introduces
> the shader_float16 extension.
>
> BUG=dawn:426
> TEST=dawn_end2end_tests
>
> Change-Id: Ie09568a416ce9eb2c11afeede3e7da520550d5fb
> Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/21901
> Commit-Queue: Xinghua Cao <xinghua.cao@intel.com>
> Reviewed-by: Corentin Wallez <cwallez@chromium.org>
> Reviewed-by: Jiawei Shao <jiawei.shao@intel.com>
> Reviewed-by: Kai Ninomiya <kainino@chromium.org>
> Reviewed-by: Austin Eng <enga@chromium.org>

Bug: chromium:1087896, dawn:426
Change-Id: I2c4465fb2fe957966b44d3e5840112219481c639
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/22781
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
diff --git a/src/dawn_native/Extensions.cpp b/src/dawn_native/Extensions.cpp
index ee3e460..d356616 100644
--- a/src/dawn_native/Extensions.cpp
+++ b/src/dawn_native/Extensions.cpp
@@ -35,6 +35,11 @@
               {"texture_compression_bc", "Support Block Compressed (BC) texture formats",
                "https://bugs.chromium.org/p/dawn/issues/detail?id=42"},
               &WGPUDeviceProperties::textureCompressionBC},
+             {Extension::ShaderFloat16,
+              {"shader_float16",
+               "Support 16bit float arithmetic and declarations in uniform and storage buffers",
+               "https://bugs.chromium.org/p/dawn/issues/detail?id=426"},
+              &WGPUDeviceProperties::shaderFloat16},
              {Extension::PipelineStatisticsQuery,
               {"pipeline_statistics_query", "Support Pipeline Statistics Query",
                "https://bugs.chromium.org/p/dawn/issues/detail?id=434"},