Fix issue with webview not ready

Some times, webview can return 0 for getWidth().  Guard against this
when taking a webview snapshot.

Change-Id: Id4d40aa90afcb86860237eac084c082b2bc012aa
diff --git a/src/com/android/browser/PhoneUi.java b/src/com/android/browser/PhoneUi.java
index e629952..da5b01c 100644
--- a/src/com/android/browser/PhoneUi.java
+++ b/src/com/android/browser/PhoneUi.java
@@ -288,7 +288,7 @@
 
         Bitmap sbm;
         WebView webView = getWebView();
-        if (webView != null) {
+        if (webView != null && webView.getWidth() != 0) {
             int view_width = webView.getWidth();
             int capture_width = mActivity.getResources().getDimensionPixelSize(
                     R.dimen.tab_thumbnail_width);