Check class name type on Grid cell mouse over (#10194)

* Check whether className is of type string

* Move string type checker method to widget util

* Fix formatting of WidgetUtil

* Break svg into lines

2 files changed, 19 insertions, 1 deletions

diff --git a/client/src/main/java/com/vaadin/client/WidgetUtil.java b/client/src/main/java/com/vaadin/client/WidgetUtil.java
index 94439dc945..e6304343aa 100644
--- a/client/src/main/java/com/vaadin/client/WidgetUtil.java
+++ b/client/src/main/java/com/vaadin/client/WidgetUtil.java
@@ -1867,6 +1867,19 @@ public class WidgetUtil {
     }
 
     /**
+     * Returns whether the given object is a string.
+     *
+     * @param obj
+     *            the object of which the type is examined
+     * @return {@code true} if the object is a string; {@code false} if not
+     * @since
+     */
+    public static native boolean isString(Object obj)
+    /*-{
+        return typeof obj === 'string' || obj instanceof String;
+    }-*/;
+
+    /**
      * Utility methods for displaying error message on components.
      *
      * @since 8.2
diff --git a/client/src/main/java/com/vaadin/client/widgets/Grid.java b/client/src/main/java/com/vaadin/client/widgets/Grid.java
index 43f85a9848..4651c534dc 100755
--- a/client/src/main/java/com/vaadin/client/widgets/Grid.java
+++ b/client/src/main/java/com/vaadin/client/widgets/Grid.java
@@ -7528,7 +7528,12 @@ public class Grid<T> extends ResizeComposite implements HasSelectionHandlers<T>,
             boolean isElement = Element.is(n);
             if (isElement) {
                 String className = Element.as(n).getClassName();
-                if (className.contains(getStylePrimaryName() + "-spacer")) {
+
+                // Also check whether className is indeed a string. For
+                // SVGElement it may be of type SVGAnimatedString.
+                // https://developer.mozilla.org/en-US/docs/Web/API/Element/className#Notes
+                if (WidgetUtil.isString(className) && className
+                        .contains(getStylePrimaryName() + "-spacer")) {
                     return true;
                 }
             }