Update angle_assert_always_on condition.

A prior CL would miss the standalone case.

Bug: chromium:1227171
Change-Id: Ib1c06d0ae7eed0feb082516690b227b964de72b0
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3048853
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>

gni/angle.gni

@@ -68,7 +68,7 @@ if (angle_has_build) {
 angle_data_dir = "angledata"
 
 declare_args() {
-  angle_assert_always_on = build_with_chromium && dcheck_always_on
+  angle_assert_always_on = dcheck_always_on
 
   if (current_cpu == "arm64" || current_cpu == "x64" ||
       current_cpu == "mips64el" || current_cpu == "s390x" ||