Make RectFSpringAnim resilient to negative height starting rect.

Test: ran tapl tests, failed before, passed after
Change-Id: I10b82dd348b5c12550e60b145c76dad542aa56e8
diff --git a/quickstep/recents_ui_overrides/src/com/android/quickstep/util/RectFSpringAnim.java b/quickstep/recents_ui_overrides/src/com/android/quickstep/util/RectFSpringAnim.java
index c6eafe6..a59c99c 100644
--- a/quickstep/recents_ui_overrides/src/com/android/quickstep/util/RectFSpringAnim.java
+++ b/quickstep/recents_ui_overrides/src/com/android/quickstep/util/RectFSpringAnim.java
@@ -165,7 +165,7 @@
         mRectYAnim = new FlingSpringAnim(this, RECT_Y, startY, endY, startVelocityY,
                 mMinVisChange, minYValue, maxYValue, springVelocityFactor, onYEndListener);
 
-        float minVisibleChange = 1f / mStartRect.height();
+        float minVisibleChange = Math.abs(1f / mStartRect.height());
         mRectScaleAnim = new SpringAnimation(this, RECT_SCALE_PROGRESS)
                 .setSpring(new SpringForce(1f)
                 .setDampingRatio(SpringForce.DAMPING_RATIO_LOW_BOUNCY)