Fix CMake build failures after recent changes

- https://dawn-review.googlesource.com/c/dawn/+/62580
  Don't add_library for targets that just generate files.
- https://dawn-review.googlesource.com/c/dawn/+/64420
  Add missing file.

Build tested locally, on macOS (only).

Bug: dawn:1080, dawn:809
Change-Id: Ia07d040dd5d3f57aa422765270c961ea6e79e3cd
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/64702
Commit-Queue: Kai Ninomiya <kainino@chromium.org>
Commit-Queue: Austin Eng <enga@chromium.org>
Auto-Submit: Kai Ninomiya <kainino@chromium.org>
Reviewed-by: Austin Eng <enga@chromium.org>

src/dawn/CMakeLists.txt

@@ -97,10 +97,8 @@ DawnJSONGenerator(
     PRINT_NAME "WebGPU headers"
     RESULT_VARIABLE "WEBGPU_HEADERS_GEN_SOURCES"
 )
-
-add_library(webgpu_headers STATIC ${DAWN_DUMMY_FILE})
-target_sources(webgpu_headers PRIVATE
-    ${WEBGPU_HEADERS_GEN_SOURCES}
+add_custom_target(webgpu_headers_gen
+    DEPENDS ${WEBGPU_HEADERS_GEN_SOURCES}
 )
 
 DawnJSONGenerator(
@@ -108,8 +106,6 @@ DawnJSONGenerator(
     PRINT_NAME "Emscripten WebGPU bits"
     RESULT_VARIABLE "EMSCRIPTEN_BITS_GEN_SOURCES"
 )
-
-add_library(emscripten_bits STATIC ${DAWN_DUMMY_FILE})
-target_sources(emscripten_bits PRIVATE
-    ${EMSCRIPTEN_BITS_GEN_SOURCES}
+add_custom_target(emscripten_bits_gen
+    DEPENDS ${EMSCRIPTEN_BITS_GEN_SOURCES}
 )

src/dawn_native/CMakeLists.txt

@@ -50,6 +50,8 @@ target_sources(dawn_native PRIVATE
     "BuddyMemoryAllocator.h"
     "Buffer.cpp"
     "Buffer.h"
+    "BufferLocation.cpp"
+    "BufferLocation.h"
     "CachedObject.cpp"
     "CachedObject.h"
     "CallbackTaskManager.cpp"