Remove Node.prefix so it's no longer visible to script.

LayoutTests/fast/dom/Node/script-tests/initial-values.js

 description("Test creation of each type of Node and check intial values")
 
 var xmlDoc = document.implementation.createDocument("http://www.w3.org/1999/xhtml", "html", null);
 
 debug("Attribute creation using createElement on an HTML doc:")
 var attr = document.createAttribute("foo");
 shouldBe("attr.nodeName", "'foo'");
 shouldBe("attr.name", "'foo'");
 // Spec: http://www.w3.org/TR/DOM-Level-2-Core/core.html#Level-2-Core-DOM-createAttribute
 // Both FF and WebKit return "foo" for Attribute.localName, even though the spec says null
@@ skipping 32 matching lines @@
 shouldBe("attr.localName", "'foo'");
 shouldBe("attr.namespaceURI", "'http://www.example.com'");
 shouldBe("attr.prefix", "'example'");
 shouldBe("attr.nodeValue", "''");
 shouldBe("attr.value", "''");
 
 var comment = document.createComment("foo");
 shouldBe("comment.nodeName", "'#comment'");
 shouldBe("comment.localName", "null");
 shouldBe("comment.namespaceURI", "null");
-shouldBe("comment.prefix", "null");
 shouldBe("comment.nodeValue", "'foo'");
 shouldBe("comment.data", "'foo'");
 
 shouldThrow("document.createCDATASection('foo')");
 var cdata = xmlDoc.createCDATASection("foo");
 shouldBe("cdata.nodeName", "'#cdata-section'");
 shouldBe("cdata.localName", "null");
 shouldBe("cdata.namespaceURI", "null");
-shouldBe("cdata.prefix", "null");
 shouldBe("cdata.nodeValue", "'foo'");
 shouldBe("cdata.data", "'foo'");
 
 var fragment = document.createDocumentFragment();
 shouldBe("fragment.nodeName", "'#document-fragment'");
 shouldBe("fragment.localName", "null");
 shouldBe("fragment.namespaceURI", "null");
-shouldBe("fragment.prefix", "null");
 shouldBe("fragment.nodeValue", "null");
 
 var doc = document.implementation.createDocument("http://www.w3.org/1999/xhtml", "html", null);
 shouldBe("doc.nodeName", "'#document'");
 shouldBe("doc.localName", "null");
 // Spec: http://www.w3.org/TR/DOM-Level-2-Core/core.html#Level-2-Core-DOM-createDocument
 // Currently both FF and WebKit return null here, disagreeing with the spec
 shouldBe("doc.namespaceURI", "'http://www.w3.org/1999/xhtml'");
-shouldBe("doc.prefix", "null");
 shouldBe("doc.nodeValue", "null");
 
 var doctype = document.implementation.createDocumentType("svg", "-//W3C//DTD SVG 1.1//EN", "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd");
 shouldBe("doctype.nodeName", "'svg'");
 shouldBe("doctype.name", "'svg'");
 shouldBe("doctype.localName", "null");
 shouldBe("doctype.namespaceURI", "null");
-shouldBe("doctype.prefix", "null");
 shouldBe("doctype.nodeValue", "null");
 
 debug("Element creation using createElement on an HTML doc:")
 var element = document.createElement("pre");
 shouldBe("element.nodeName", "'PRE'");
 // Spec: http://www.w3.org/TR/DOM-Level-2-Core/core.html#Level-2-Core-DOM-createElement
 // FF returns "PRE" for localName, WebKit returns "pre", the spec says we should return null
 shouldBe("element.localName", "null");
 // FF returns null for namespaceURI, WebKit returns http://www.w3.org/1999/xhtml, the spec says we should return null
 shouldBe("element.namespaceURI", "null");
@@ skipping 56 matching lines @@
 shouldBe("element.namespaceURI", "'http://www.w3.org/1999/xhtml'");
 shouldBe("element.prefix", "'html'");
 shouldBe("element.nodeValue", "null");
 shouldBe("element.attributes.toString()", "'[object NamedNodeMap]'");
 
 debug("Processing instruction creation using createProcessingInstruction on an HTML doc:")
 var processingInstruction = document.createProcessingInstruction('xml-stylesheet', 'type="text/xsl" href="missing.xsl"');
 shouldBe("processingInstruction.nodeName", "'xml-stylesheet'");
 shouldBe("processingInstruction.localName", "null");
 shouldBe("processingInstruction.namespaceURI", "null");
-shouldBe("processingInstruction.prefix", "null");
 // DOM Core Level 2 and DOM Core Level 3 disagree on ProcessingInstruction.nodeValue
 // L2: entire content excluding the target
 // L3: same as ProcessingInstruction.data
 // We're following Level 3
 shouldBe("processingInstruction.nodeValue", "'type=\"text/xsl\" href=\"missing.xsl\"'");
 shouldBe("processingInstruction.target", "'xml-stylesheet'");
 shouldBe("processingInstruction.data", "'type=\"text/xsl\" href=\"missing.xsl\"'");
 
 debug("Processing instruction creation using createProcessingInstruction on an XHTML doc:")
 processingInstruction = xmlDoc.createProcessingInstruction('xml-stylesheet', 'type="text/xsl" href="missing.xsl"');
 shouldBe("processingInstruction.nodeName", "'xml-stylesheet'");
 shouldBe("processingInstruction.localName", "null");
 shouldBe("processingInstruction.namespaceURI", "null");
-shouldBe("processingInstruction.prefix", "null");
 shouldBe("processingInstruction.nodeValue", "'type=\"text/xsl\" href=\"missing.xsl\"'");
 shouldBe("processingInstruction.target", "'xml-stylesheet'");
 shouldBe("processingInstruction.data", "'type=\"text/xsl\" href=\"missing.xsl\"'");
 
 debug("Text node creation using createTextNode on an HTML doc:")
 var text = document.createTextNode("foo");
 shouldBe("text.nodeName", "'#text'");
 shouldBe("text.localName", "null");
 shouldBe("text.namespaceURI", "null");
-shouldBe("text.prefix", "null");
 shouldBe("text.nodeValue", "'foo'");
 shouldBe("text.data", "'foo'");