Move theme name mangling to where it is actually desired (#9891)

Change-Id: Ia78d38c36e7f5f9c86e645f4afd2014cdc88cb32

client/src/com/vaadin/client/ApplicationConfiguration.java

     }
 
     public String getThemeName() {
-        String themeName = getJsoConfiguration(id).getConfigString("theme");
-        themeName = themeName.replaceAll("[^a-zA-Z0-9]", "");
-        return themeName;
+        return getJsoConfiguration(id).getConfigString("theme");
     }
 
     public String getThemeUri() {

client/src/com/vaadin/client/ui/ui/UIConnector.java

         // the user
         root.getElement().setInnerHTML("");
 
-        root.addStyleName("v-theme-"
-                + applicationConnection.getConfiguration().getThemeName());
+        String themeName = applicationConnection.getConfiguration()
+                .getThemeName();
+        // Remove chars that are not suitable for style names
+        themeName = themeName.replaceAll("[^a-zA-Z0-9]", "");
+        root.addStyleName("v-theme-" + themeName);
 
         root.add(getWidget());