Improve our html editor; add syntax highlighting for script tags; hyperlink detection and navigatio…

editor/tools/plugins/com.google.dart.tools.core/src/com/google/dart/tools/core/html/XmlNode.java

Index: editor/tools/plugins/com.google.dart.tools.core/src/com/google/dart/tools/core/html/XmlNode.java
===================================================================
--- editor/tools/plugins/com.google.dart.tools.core/src/com/google/dart/tools/core/html/XmlNode.java	(revision 16584)
+++ editor/tools/plugins/com.google.dart.tools.core/src/com/google/dart/tools/core/html/XmlNode.java	(working copy)
@@ -78,8 +78,10 @@
   public int getEndOffset() {
     if (endToken != null) {
       return endToken.getLocation() + endToken.getValue().length();
+    } else if (startToken != null) {
+      return startToken.getLocation() + startToken.getValue().length();
     } else {
-      return startToken.getLocation() + startToken.getValue().length();
+      return -1;
     }
   }
 
@@ -99,12 +101,28 @@
     return label;
   }
 
+  public XmlNode getNodeFor(int offset) {
+    if (getStartOffset() <= offset && offset <= getEndOffset()) {
+      return this;
+    }
+
+    for (int i = 0; i < children.size(); i++) {
+      XmlNode node = children.get(i).getNodeFor(offset);
+
+      if (node != null) {
+        return node;
+      }
+    }
+
+    return null;
+  }
+
   public XmlNode getParent() {
     return parent;
   }
 
   public int getStartOffset() {
-    return startToken.getLocation();
+    return startToken == null ? -1 : startToken.getLocation();
   }
 
   public Token getStartToken() {