Do not show soft keyboard for readonly textfields.

Part of a fix for http://b/issue?id=2159869.  The request to show
the soft input has been moved to nativeTextInputMotionUp, where it
can check if the input field is readOnly.  This way it is also
handled by shortPressOnTextField, for when a user shortpresses
on the field.

core/java/android/webkit/WebView.java

@@ -4672,9 +4672,6 @@ public class WebView extends AbsoluteLayout
         }
         int x = viewToContentX((int) event.getX() + mWebTextView.getLeft());
         int y = viewToContentY((int) event.getY() + mWebTextView.getTop());
-        // In case the soft keyboard has been dismissed, bring it back up.
-        InputMethodManager.getInstance(getContext()).showSoftInput(mWebTextView,
-                0);
         if (nativeFocusNodePointer() != nativeCursorNodePointer()) {
             nativeMotionUp(x, y, mNavSlop);
         }