Fixed a small sizecompat check

Was only checking dev option, not actual sizecompat.

Bug: 143597834
Test: use caption to restore app in desktop.
Change-Id: I37e31212f6aee9da8c7e857c3ed7ee45f47d515e
diff --git a/services/core/java/com/android/server/wm/ActivityTaskManagerService.java b/services/core/java/com/android/server/wm/ActivityTaskManagerService.java
index da7af5f..a683ccb 100644
--- a/services/core/java/com/android/server/wm/ActivityTaskManagerService.java
+++ b/services/core/java/com/android/server/wm/ActivityTaskManagerService.java
@@ -3432,7 +3432,7 @@
 
                 if (stack.inFreeformWindowingMode()) {
                     stack.setWindowingMode(WINDOWING_MODE_FULLSCREEN);
-                } else if (!mSizeCompatFreeform) {
+                } else if (!mSizeCompatFreeform && r.inSizeCompatMode()) {
                     throw new IllegalStateException("Size-compat windows are currently not"
                             + "freeform-enabled");
                 } else if (stack.getParent().inFreeformWindowingMode()) {