Finish isolated splits API

Fixes: b/318344370
Change-Id: I160554c5bfceb3f466abde412bb3d167e4351a69
diff --git a/tools/compiledump.py b/tools/compiledump.py
index 5c926b3..f167821 100755
--- a/tools/compiledump.py
+++ b/tools/compiledump.py
@@ -582,8 +582,6 @@
         if args.enable_test_assertions:
             cmd.append('-Dcom.android.tools.r8.enableTestAssertions=1')
         feature_jars = dump.feature_jars()
-        if determine_isolated_splits(build_properties, feature_jars):
-            cmd.append('-Dcom.android.tools.r8.isolatedSplits=1')
         if args.print_times:
             cmd.append('-Dcom.android.tools.r8.printtimes=1')
         if args.r8_flags:
@@ -625,6 +623,8 @@
                 ])
             else:
                 cmd.append(feature_jar)
+        if determine_isolated_splits(build_properties, feature_jars):
+            cmd.append('--isolated-splits')
         if dump.library_jar():
             cmd.extend(['--lib', dump.library_jar()])
         if dump.classpath_jar() and not is_l8_compiler(compiler):