Do not allow text selection if there is no ActionBar.

Bug:3276538
Change-Id: I060f14471e26e4bc1bf9773b847e0dbac9228426
diff --git a/core/java/android/webkit/SelectActionModeCallback.java b/core/java/android/webkit/SelectActionModeCallback.java
index 54c9d9a..86a67c7 100644
--- a/core/java/android/webkit/SelectActionModeCallback.java
+++ b/core/java/android/webkit/SelectActionModeCallback.java
@@ -34,7 +34,11 @@
     }
 
     void finish() {
-        mActionMode.finish();
+        // It is possible that onCreateActionMode was never called, in the case
+        // where there is no ActionBar, for example.
+        if (mActionMode != null) {
+            mActionMode.finish();
+        }
     }
 
     // ActionMode.Callback implementation