Bug 1834558: chore(webgpu): sync `.gitignore` with `.hgignore` for WebGPU r=webgpu-reviewers,nical

Depends on D181307

Differential Revision: https://phabricator.services.mozilla.com/D181308

.gitignore

@@ -118,6 +118,11 @@ devtools/**/node_modules
 # Ignore browsertime output directory
 browsertime-results
 
+# Ignore the build directories of WebGPU and WebRender standalone builds.
+gfx/wgpu/target
+gfx/wgpu/.*/build
+gfx/wr/target/
+
 # Tag files generated by GNU Global
 GTAGS
 GRTAGS
@@ -141,6 +146,7 @@ mobile/android/gradle/.gradle
 /servo/ports/geckolib/target/
 /dom/base/rust/target/
 /servo/components/style/target/
+/dom/webgpu/tests/cts/vendor/target/
 
 # Ignore mozharness execution files
 testing/mozharness/.tox/