Fixes incorrect CMake path. Should be using header, not source.

Change-Id: Ibcb5f370e312adc209bfa261f8474a8016d11d08
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/200214
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Loko Kung <lokokung@google.com>
Auto-Submit: Loko Kung <lokokung@google.com>
diff --git a/src/dawn/utils/CMakeLists.txt b/src/dawn/utils/CMakeLists.txt
index 21b818e..bc77549 100644
--- a/src/dawn/utils/CMakeLists.txt
+++ b/src/dawn/utils/CMakeLists.txt
@@ -71,7 +71,7 @@
     "BinarySemaphore.h"
     "TerribleCommandBuffer.h"
     "TestUtils.h"
-    "WireHelper.cpp"
+    "WireHelper.h"
   SOURCES
     "BinarySemaphore.cpp"
     "TerribleCommandBuffer.cpp"