WebGPU: Fix timestamp quantization with --enable-webgpu-developer-fea…

…tures

Also need to disable timestamp quantization when the WebGPU developer features is enabled, otherwise it may always be enabled due to Dawn's default behavior(actually it's enabled by default in Dawn).

Bug: dawn:1800
Change-Id: Ifc44a31ef367378b53caf18b324bc8d372f5b39c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4977720
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Commit-Queue: Hao Li <hao.x.li@intel.com>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1216688}

gpu/command_buffer/service/webgpu_decoder_impl.cc

@@ -1391,6 +1391,8 @@ void WebGPUDecoderImpl::RequestDeviceImpl(
   // --enable-webgpu-developer-features is used.
   if (!enable_webgpu_developer_features_) {
     require_device_enabled_toggles.push_back("timestamp_quantization");
+  } else {
+    require_device_disabled_toggles.push_back("timestamp_quantization");
   }
   // Disable the blob cache if we don't have an isolation key.
   if (isolation_key_->empty()) {