Change default suggestion popup width in ComboBox (#91)

Closes vaadin/framework8-issues#522

server/src/main/java/com/vaadin/ui/ComboBox.java

     }
 
     /**
-     * Returns the suggestion pop-up's width as a CSS string.
+     * Returns the suggestion pop-up's width as a CSS string. By default this
+     * width is set to "100%".
      *
      * @see #setPopupWidth
      * @since 7.7
      * Returns the empty selection caption.
      * <p>
      * The empty string {@code ""} is the default empty selection caption.
-     * 
+     *
      * @see #setEmptySelectionAllowed(boolean)
      * @see #isEmptySelectionAllowed()
      * @see #setEmptySelectionCaption(String)
      * @see #isSelected(Object)
      * @see #select(Object)
-     * 
+     *
      * @return the empty selection caption, not {@code null}
      */
     public String getEmptySelectionCaption() {
      * Sets the suggestion pop-up's width as a CSS string. By using relative
      * units (e.g. "50%") it's possible to set the popup's width relative to the
      * ComboBox itself.
+     * <p>
+     * By default this width is set to "100%" so that the pop-up's width is
+     * equal to the width of the combobox. By setting width to null the pop-up's
+     * width will automatically expand beyond 100% relative width to fit the
+     * content of all displayed items.
      *
      * @see #getPopupWidth()
      * @since 7.7
     /**
      * Sets whether to scroll the selected item visible (directly open the page
      * on which it is) when opening the combo box popup or not.
-     *
+     * <p>
      * This requires finding the index of the item, which can be expensive in
      * many large lazy loading containers.
      *

shared/src/main/java/com/vaadin/shared/ui/combobox/ComboBoxState.java

      * itself.
      */
     @DelegateToWidget
-    public String suggestionPopupWidth = null;
+    public String suggestionPopupWidth = "100%";
 
     /**
      * True to allow the user to send new items to the server, false to only

tests/screenshots

-Subproject commit 46b036dd9ac418341d489631090bc33ad310ba72
+Subproject commit 53c0f6fb288dbc91387fd8bb40038ff48bbd7a32