[DevTools] Migrate RequestHeadersView to TreeOutlineInShadow.

third_party/WebKit/Source/devtools/front_end/ui/treeoutline.js

Index: third_party/WebKit/Source/devtools/front_end/ui/treeoutline.js
diff --git a/third_party/WebKit/Source/devtools/front_end/ui/treeoutline.js b/third_party/WebKit/Source/devtools/front_end/ui/treeoutline.js
index f5c7e62bbeaa83f2249b2c7e68f6379ca659650a..88a8d74fa8fa4309decd37030b498880bdedf86f 100644
--- a/third_party/WebKit/Source/devtools/front_end/ui/treeoutline.js
+++ b/third_party/WebKit/Source/devtools/front_end/ui/treeoutline.js
@@ -342,6 +342,11 @@ TreeOutlineInShadow.prototype = {
         this._disclosureElement.classList.add("tree-outline-disclosure-hide-overflow");
     },
 
+    makeDense: function()
+    {
+        this.contentElement.classList.add("tree-outline-dense");
+    },
+
     __proto__: TreeOutline.prototype
 }