remove experimental 'reveal' mode... we will provide something similar

but as a different element

core-header-panel.css

@@ -64,24 +64,3 @@ mode: cover
   bottom: 0;
   left: 0;
 }
-
-/*
-mode: reveal
-*/
-/*@polyfill :host([mode=reveal]) #outerContainer > .core-header, :host([mode=reveal]) #outerContainer > core-toolbar */
-:host([mode=reveal]) ::content#headerContent > * {
-  z-index: 1;
-}
-
-:host([mode=reveal]) #mainPanel {
-  position: static;
-}
-
-:host([mode=reveal]) #mainContainer {
-  position: absolute;
-  top: 0;
-  right: 0;
-  bottom: 0;
-  left: 0;
-}
-

core-header-panel.html

@@ -50,7 +50,7 @@
 
     <core-layout id="mainPanel" core-flex>
 
-      <div id="mainContainer" core-flex?="{{mode !== 'cover' && mode != 'reveal'}}" on-scroll="{{scroll}}">
+      <div id="mainContainer" core-flex?="{{mode !== 'cover'}}" on-scroll="{{scroll}}">
         <content id="mainContent" select="*"></content>
       </div>
 
@@ -122,31 +122,22 @@
        * @default false
        */
       shadow: false,
-
     },
 
-    prevScrollTop: 0,
-
     attached: function() {
-      this.async('scroll', null, 100);
+      this.async('scroll');
     },
 
     modeChanged: function() {
-      this.reset();
       this.scroll();
     },
 
     get header() {
       return this.$.headerContent.getDistributedNodes()[0];
     },
 
-    reset: function() {
-      this.$.mainContainer.style = null;
-      this.header.style = null;
-    },
-
     scroll: function() {
-      var shadowMode = {'waterfall': 1, 'waterfall-tall': 1, 'reveal': 1};
+      var shadowMode = {'waterfall': 1, 'waterfall-tall': 1};
       var noShadow = {'seamed': 1, 'cover': 1, 'scroll': 1};
       var tallMode = {'waterfall-tall': 1};
 
@@ -163,21 +154,7 @@
         if (tallMode[this.mode]) {
           header.classList.toggle(this.tallClass, atTop);
         }
-
-        if (this.mode === 'reveal') {
-          if (!this.headerHeight) {
-            this.headerHeight = header.offsetHeight;
-            main.style.paddingTop = this.headerHeight + 'px';
-          }
-
-          this.y = Math.min(this.headerHeight, 
-              Math.max((this.y || 0) + (sTop - this.prevScrollTop), 0));
-          var s = header.style;
-          s.webkitTransform = s.transform = 'translateY(' + (-this.y) + 'px)';
-        }
       }
-
-      this.prevScrollTop = sTop;
     }
 
   });

demo.html

@@ -96,10 +96,5 @@
       <div class="content" style="margin: 60px 60px 60px 0;"></div>
     </core-header-panel>
 
-    <core-header-panel mode="reveal">
-      <div class="core-header">reveal</div>
-      <div class="content"></div>
-    </core-header-panel>
-
   </body>
 </html>