Fix potential memory leak in SparseWeakArray

When compacting the array, one needs to reset the array positions that
have been moved to null.

Bug: 157444995
Test: N/A
Change-Id: I5ab17b378c318a07652291d55a600c697f097e67
(cherry picked from commit 131ce7ff651d652a77e822d0cb0b67cb2a8a1754)
diff --git a/bridge/src/com/android/layoutlib/bridge/util/SparseWeakArray.java b/bridge/src/com/android/layoutlib/bridge/util/SparseWeakArray.java
index a2a8aa9..dd06e80 100644
--- a/bridge/src/com/android/layoutlib/bridge/util/SparseWeakArray.java
+++ b/bridge/src/com/android/layoutlib/bridge/util/SparseWeakArray.java
@@ -133,6 +133,7 @@
                 if (i != o) {
                     keys[o] = keys[i];
                     values[o] = val;
+                    values[i] = null;
                 }
 
                 o++;