Removed HTMLCell from UI and added better placeholder logic.

IPython/frontend/html/notebook/static/js/panelsection.js

@@ -164,9 +164,9 b' var IPython = (function (IPython) {'
         this.content.find('#to_code').click(function () {
             IPython.notebook.to_code();
         });
-        this.content.find('#to_html').click(function () {
-            IPython.notebook.to_html();
-        });
+//        this.content.find('#to_html').click(function () {
+//            IPython.notebook.to_html();
+//        });
         this.content.find('#to_markdown').click(function () {
             IPython.notebook.to_markdown();
         });

IPython/frontend/html/notebook/static/js/textcell.js

@@ -72,6 +72,9 b' var IPython = (function (IPython) {'
             this.code_mirror.focus();
             this.code_mirror.refresh();
             this.rendered = false;
+            if (this.get_source() === this.placeholder) {
+                this.set_source('');
+            };
         };
     };
 

IPython/frontend/html/notebook/templates/notebook.html

@@ -86,7 +86,7 b''
                 <div class="section_row">
                     <span id="cell_type" class="section_row_buttons">
                         <button id="to_code">Code</button>
-                        <button id="to_html">HTML</button>
+<!--                        <button id="to_html">HTML</button>-->
                         <button id="to_markdown">Markdown</button>
                     </span>
                      <span class="button_label">Format</span>