make GWT epub friendly (#10148)

GWT is a great tool to bring interactivity in ebooks to a whole new
level. Unfortunately, the epub v3 specs are still based on XHTML... even
though the newer bells and whistles of HTML5 are acceptable too.

With respect to GWT, issue arise solely due to the ` ` character
entity, which is undefined in `XHTML`. Once replaced by ` ` GWT
works like a charm inside any epub (and javascript capable reader).

This PR does just that by replacing those characters but only where it
matters, e.g. no replacements under the `test` or `samples` directories.

Author: evoludolab

user/src/com/google/gwt/layout/client/LayoutImpl.java

@@ -54,7 +54,8 @@ class LayoutImpl {
 
   protected static DivElement createRuler(Unit widthUnit, Unit heightUnit) {
     DivElement ruler = Document.get().createDivElement();
-    ruler.setInnerHTML(" ");
+    // use ePub/XHTML friendly  
+    ruler.setInnerHTML(" ");
     Style style = ruler.getStyle();
     style.setPosition(Position.ABSOLUTE);
     style.setZIndex(-32767);

user/src/com/google/gwt/logging/client/HtmlLogFormatter.java

@@ -102,7 +102,8 @@ private String getColor(int logLevel) {
   private String getEscaped(String text) {
     text = text.replaceAll("<", "&lt;");
     text = text.replaceAll(">", "&gt;");
-    text = text.replaceAll("\t", "&nbsp;&nbsp;&nbsp;");
+    // use ePub/XHTML friendly &nbsp;
+    text = text.replaceAll("\t", "&#xA0;&#xA0;&#xA0;");
     return text;
   }
 

user/src/com/google/gwt/user/client/ui/Grid.java

@@ -75,7 +75,8 @@ public class Grid extends HTMLTable {
    */
   private static native void addRows(Element table, int rows, int columns) /*-{
      var td = $doc.createElement("td");
-     td.innerHTML = " ";
+     // use ePub/XHTML friendly  
+     td.innerHTML = " ";
      var row = $doc.createElement("tr");
      for(var cellNum = 0; cellNum < columns; cellNum++) {
        var cell = td.cloneNode(true);
@@ -130,7 +131,8 @@ public Grid(int rows, int columns) {
   public boolean clearCell(int row, int column) {
     Element td = getCellFormatter().getElement(row, column);
     boolean b = internalClearCell(td, false);
-    td.setInnerHTML("&nbsp;");
+    // use ePub/XHTML friendly &nbsp;
+    td.setInnerHTML("&#xA0;");
     return b;
   }
 
@@ -269,9 +271,9 @@ public void resizeRows(int rows) {
   protected com.google.gwt.user.client.Element createCell() {
     Element td = super.createCell();
 
-    // Add a non-breaking space to the TD. This ensures that the cell is
-    // displayed.
-    td.setInnerHTML("&nbsp;");
+    // Add an ePub/XHTML friendly non-breaking space to the TD. This ensures that
+    // the cell is displayed.
+    td.setInnerHTML("&#xA0;");
     return DOM.asOld(td);
   }
 

user/src/com/google/gwt/user/client/ui/TabBar.java

@@ -208,7 +208,8 @@ public TabBar() {
 
     panel.setVerticalAlignment(HasVerticalAlignment.ALIGN_BOTTOM);
 
-    HTML first = new HTML(" ", true), rest = new HTML(" ", true);
+    // use ePub/XHTML friendly  
+    HTML first = new HTML(" ", true), rest = new HTML(" ", true);
     first.setStyleName("gwt-TabBarFirst");
     rest.setStyleName("gwt-TabBarRest");
     first.setHeight("100%");