Move 712-varhandle-invocations to API level 28

Bug: 65168732
Test: art/test/run-test  --no-relocate --64 --build-with-javac-dx --runtime-option -Xcheck:jni --never-clean --host 712-varhandle-invocations
Change-Id: Ie8cab287541dd82324cc8bb8365bd31c552d0518
diff --git a/test/712-varhandle-invocations/build b/test/712-varhandle-invocations/build
index 6d4429f..253765b 100755
--- a/test/712-varhandle-invocations/build
+++ b/test/712-varhandle-invocations/build
@@ -35,8 +35,5 @@
 # Desugar is not happy with our Java 9 byte code, it shouldn't be necessary here anyway.
 export USE_DESUGAR=false
 
-# See b/65168732
-export USE_D8=false
-
 # Invoke default build with increased heap size for dx
 ./default-build "$@" --experimental var-handles --dx-vm-option -JXmx384m
diff --git a/test/etc/default-build b/test/etc/default-build
index dd55602..8bb898c 100755
--- a/test/etc/default-build
+++ b/test/etc/default-build
@@ -145,7 +145,7 @@
 declare -A DX_EXPERIMENTAL_ARGS
 DX_EXPERIMENTAL_ARGS["method-handles"]="--min-sdk-version=26"
 DX_EXPERIMENTAL_ARGS["parameter-annotations"]="--min-sdk-version=25"
-DX_EXPERIMENTAL_ARGS["var-handles"]="--min-sdk-version=26"
+DX_EXPERIMENTAL_ARGS["var-handles"]="--min-sdk-version=28"
 
 while true; do
   if [ "x$1" = "x--dx-option" ]; then