Disable FontName, FontSize, and FontSizeDelta commands in contenteditable=plaintext-only.

third_party/WebKit/LayoutTests/fast/forms/plaintext-mode-1.html

 <script>
 
 function log(message)
 {
     var li = document.createElement("li");
     li.appendChild(document.createTextNode(message));
     var console = document.getElementById("console");
     console.appendChild(li);
 }
 
@@ skipping 20 matching lines @@
 var e = document.getElementById("textfield");
 e.focus();
 e.setSelectionRange(0, 5);
 
 assert("document.queryCommandEnabled", "BackColor", false);
 assert("document.queryCommandEnabled", "Bold", false);
 assert("document.queryCommandEnabled", "Copy", true);
 assert("document.queryCommandEnabled", "CreateLink", false);
 assert("document.queryCommandEnabled", "Cut", true);
 assert("document.queryCommandEnabled", "Delete", true);
-assert("document.queryCommandEnabled", "FontName", true); // Shouldn't this be false?
-assert("document.queryCommandEnabled", "FontSize", true); // Shouldn't this be false?
-assert("document.queryCommandEnabled", "FontSizeDelta", true); // Shouldn't this be false?
+assert("document.queryCommandEnabled", "FontName", false);
+assert("document.queryCommandEnabled", "FontSize", false);
+assert("document.queryCommandEnabled", "FontSizeDelta", false);
 assert("document.queryCommandEnabled", "ForeColor", false);
 assert("document.queryCommandEnabled", "ForwardDelete", true);
 assert("document.queryCommandEnabled", "Indent", false);
 assert("document.queryCommandEnabled", "InsertHTML", true);
 assert("document.queryCommandEnabled", "InsertImage", false);
 assert("document.queryCommandEnabled", "InsertLineBreak", true);
 assert("document.queryCommandEnabled", "InsertParagraph", true);
 assert("document.queryCommandEnabled", "InsertNewlineInQuotedContent", false);
 assert("document.queryCommandEnabled", "InsertText", true);
 assert("document.queryCommandEnabled", "Italic", false);
@@ skipping 16 matching lines @@
 e.setSelectionRange(3, 3);
 assert("document.queryCommandEnabled", "Transpose", true);
 
 e.setSelectionRange(0, 5);
 assert("document.execCommand", "Cut", true);
 assert("document.queryCommandEnabled", "Undo", true);
 assert("document.execCommand", "Undo", true);
 assert("document.queryCommandEnabled", "Redo", true);
 
 </script>