BUILD.gn: Remove the temporary group with Dawn migrated.

Bug: dawn:706
Change-Id: I60aa97845cdfce263afc34947c597ceb5b8e6fb0
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/44861
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
diff --git a/BUILD.gn b/BUILD.gn
index bec67c8..56b73e1 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -12,15 +12,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import("//build_overrides/build.gni")
-import("tint_overrides_with_defaults.gni")
-
-# Temporary group to not break dependents while they rename their Tint GN
-# targets
-group("libtint") {
-  public_deps = [ "src:libtint" ]
-}
-
 # This target is built when no specific target is specified on the command line.
 group("default") {
   testonly = true