Revert "[dawn][emscripten][test] Add workaround for WASM tests startup."

This reverts commit 479c0326bd78e5069928c292d97dec22542749d7.

Reason for revert: The Chromium change was reverted.

Original change's description:
> [dawn][emscripten][test] Add workaround for WASM tests startup.
>
> - In g3, we are seeing test flakes for the first WebGPU tests
>   to run. This is likely a regression in Chromium, and we are
>   investigating further. In the meantime, this workaround works
>   locally in g3 to make the flake almost never happen since
>   the issue is believed to be a race between the tests and
>   Chromium startup.
>
> Bug: 404535888
> No-Try: true
> Change-Id: I9085bb3e6ce62d72f2759204306462484342529c
> Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/231678
> Reviewed-by: Kai Ninomiya <kainino@chromium.org>
> Commit-Queue: Loko Kung <lokokung@google.com>

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 404535888
Fixed: 405952961
Change-Id: Ia0dc415206c8103cb6d8d174b82cfa0903e2fe33
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/239475
Commit-Queue: Kai Ninomiya <kainino@chromium.org>
Reviewed-by: Loko Kung <lokokung@google.com>
Auto-Submit: Kai Ninomiya <kainino@chromium.org>
diff --git a/src/emdawnwebgpu/tests/FuturesTests.cpp b/src/emdawnwebgpu/tests/FuturesTests.cpp
index 296ccea1..aae545bd1 100644
--- a/src/emdawnwebgpu/tests/FuturesTests.cpp
+++ b/src/emdawnwebgpu/tests/FuturesTests.cpp
@@ -26,7 +26,6 @@
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #include <dawn/webgpu_cpp_print.h>
-#include <emscripten.h>
 #include <gmock/gmock.h>
 #include <gtest/gtest.h>
 #include <webgpu/webgpu_cpp.h>
@@ -51,14 +50,6 @@
 
   protected:
     wgpu::Adapter RequestAdapter(const wgpu::RequestAdapterOptions* adapterOptions = nullptr) {
-        // TODO(crbug.com/404535888): Remove this sleep once we figure out regression.
-        static bool sSleepWorkaround = false;
-        if (!sSleepWorkaround) {
-            // Make the test sleep for an additional 2 seconds before trying to requestAdapter.
-            emscripten_sleep(2000);
-            sSleepWorkaround = true;
-        }
-
         wgpu::RequestAdapterStatus status;
         wgpu::Adapter result = nullptr;
         EXPECT_EQ(instance.WaitAny(