Fix cache default on condition.

- Messed up the conditon in previous change so it required both the
  enable flag to be on and the disable to be off, but then we can't
  deprecate the enable flag in Chromium.

Bug: dawn:549
Change-Id: I1c730939104aafaef48182238fa32ed7fa6a1e16
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/110983
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Austin Eng <enga@chromium.org>
Commit-Queue: Loko Kung <lokokung@google.com>

src/dawn/native/Device.cpp

@@ -618,7 +618,7 @@ BlobCache* DeviceBase::GetBlobCache() {
     // TODO(crbug.com/dawn/1481): Shader caching currently has a dependency on the WGSL writer to
     // generate cache keys. We can lift the dependency once we also cache frontend parsing,
     // transformations, and reflection.
-    if (IsToggleEnabled(Toggle::EnableBlobCache) && !IsToggleEnabled(Toggle::DisableBlobCache)) {
+    if (!IsToggleEnabled(Toggle::DisableBlobCache)) {
         return mAdapter->GetInstance()->GetBlobCache();
     }
 #endif