Actually pass the instance descriptor in APICreateInstance

This argument was getting dropped, so the default descriptor was
always used.

Bug: chromium:1343047
Change-Id: I521e00a3c390ff193fcc18072a037c069e98c680
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/95982
Commit-Queue: Austin Eng <enga@chromium.org>
Reviewed-by: Shrek Shao <shrekshao@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>

src/dawn/native/Instance.cpp

@@ -103,7 +103,7 @@ dawn::platform::CachingInterface* GetCachingInterface(dawn::platform::Platform*
 }  // anonymous namespace
 
 InstanceBase* APICreateInstance(const InstanceDescriptor* descriptor) {
-    return InstanceBase::Create().Detach();
+    return InstanceBase::Create(descriptor).Detach();
 }
 
 // InstanceBase