[DevTools] Add "never show" link to emulation warning.

Source/devtools/front_end/responsiveDesignView.css

Index: Source/devtools/front_end/responsiveDesignView.css
diff --git a/Source/devtools/front_end/responsiveDesignView.css b/Source/devtools/front_end/responsiveDesignView.css
index 7ebc5e0ce86136bdf1c0423262a478285dbe2260..36e9989a6e1a74145a3a361e52e13db69ea476d8 100644
--- a/Source/devtools/front_end/responsiveDesignView.css
+++ b/Source/devtools/front_end/responsiveDesignView.css
@@ -439,6 +439,12 @@
     flex: none;
 }
 
+.responsive-design-warning .disable-warning {
+    margin-right: 5px;
+    text-decoration: underline;
+    cursor: pointer;
+}
+
 .responsive-design-toggle-media-inspector .glyph {
     background-color: rgb(180, 180, 180);
     -webkit-mask-position: -128px -48px;