Publish Vulpes Preview 15 sources for desktop, Android and Tundra

Share Gaia assets and adapters, keep private profiles and development documents local, and update both public READMEs.

gaia/shared/js/sticky_header.js

@@ -0,0 +1,44 @@
+/* exported StickyHeader */
+
+function StickyHeader(scrollable, sticky) {
+  'use strict';
+
+  var headers = scrollable.getElementsByTagName('header');
+  var stickyPosition;
+  var stickyStyle = sticky.style;
+
+  this._throttledRefresh = function() {
+    var display = false;
+    if (stickyPosition === undefined) {
+      stickyPosition = sticky.offsetHeight + sticky.offsetTop;
+    }
+    for (var i = 1, length = headers.length; i < length; i++) {
+      if (headers[i].offsetTop - scrollable.scrollTop > stickyPosition) {
+
+        // While reflecting a header, make sure to not reflect a header
+        // that is not displayed.
+        var lookupIndex = 1;
+        var header = headers[i - lookupIndex];
+        while (header && header.offsetHeight === 0) {
+          lookupIndex++;
+          header = headers[i - lookupIndex];
+        }
+
+        stickyStyle.backgroundImage = '-moz-element(#' + header.id + ')';
+        display = true;
+        break;
+      }
+    }
+
+    sticky.classList.toggle('has-content', display);
+    this.throttle = null;
+  }.bind(this);
+
+  this.refresh = function() {
+    if (!this.throttle) {
+      this.throttle = setTimeout(this._throttledRefresh, 0);
+    }
+  }.bind(this);
+
+  scrollable.addEventListener('scroll', this.refresh);
+}