Add a UA style, "display: contents", for <slot>

third_party/WebKit/public/blink_resources.grd

Index: third_party/WebKit/public/blink_resources.grd
diff --git a/third_party/WebKit/public/blink_resources.grd b/third_party/WebKit/public/blink_resources.grd
index 4c57bf32324b1f13bb466fe40534f67a171fcec1..dc5d8392f155d436762aec2d72bf11c927e838e0 100644
--- a/third_party/WebKit/public/blink_resources.grd
+++ b/third_party/WebKit/public/blink_resources.grd
@@ -25,6 +25,7 @@
       <include name="IDR_UASTYLE_MATHML_CSS" file="../Source/core/css/mathml.css" type="BINDATA"/>
       <include name="IDR_UASTYLE_MEDIA_CONTROLS_CSS" file="../Source/core/css/mediaControls.css" type="BINDATA"/>
       <include name="IDR_UASTYLE_FULLSCREEN_CSS" file="../Source/core/css/fullscreen.css" type="BINDATA"/>
+      <include name="IDR_UASTYLE_SLOT_CSS" file="../Source/core/css/slot.css" type="BINDATA"/>
       <include name="IDR_UASTYLE_XHTMLMP_CSS" file="../Source/core/css/xhtmlmp.css" type="BINDATA"/>
       <include name="IDR_UASTYLE_VIEWPORT_ANDROID_CSS" file="../Source/core/css/viewportAndroid.css" type="BINDATA"/>
       <include name="IDR_UASTYLE_VIEWPORT_TELEVISION_CSS" file="../Source/core/css/viewportTelevision.css" type="BINDATA"/>