Prevent rasterization artefacts in the logo, and simplify markup.

- Remove sketch-namespaced attributes.
 - Remove unused groups, and cancel out unnecessary transforms.
 - Use overlap to avoid rasterization artefacts in the logo.
 - Extend comment for `#logo` click event handler, as it's a non-obvious hack for Safari.
 - Remove viewBox parameter and define paths in their final form.

app/assets/javascripts/logo.js.coffee

@@ -44,6 +44,7 @@ $(document).on('page:fetch',  start)
 $(document).on('page:change', stop)
 
 $ ->
-  # Make logo clickable
+  # Make logo clickable as part of a workaround for Safari visited
+  # link behaviour (See !2690).
   $('#logo').on 'click', ->
     $('#js-shortcuts-home').get(0).click()

app/views/shared/_logo.svg

@@ -1,21 +1,9 @@
-<svg width="36px" height="36px" viewBox="0 0 210 210" version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" id="tanuki-logo">
-    <g id="Page-1" stroke="none" stroke-width="1" fill="none" fill-rule="evenodd" sketch:type="MSPage">
-        <g id="logo" sketch:type="MSLayerGroup" transform="translate(0.000000, 10.000000)">
-            <g id="Page-1" sketch:type="MSShapeGroup">
-                <g id="Fill-1-+-Group-24">
-                    <g id="Group-24">
-                        <g id="Group">
-                            <path id="tanuki-right-ear"   d="M12.2685,74.7342 L66.4215,74.7342 L43.1485,3.1092 C41.9515,-0.5768 36.7375,-0.5758 35.5405,3.1092 L12.2685,74.7342 L12.2685,74.7342 Z" fill="#E24329" class="tanuki-shape"></path>
-                            <path id="tanuki-right-cheek" d="M12.2685,74.7341 L12.2685,74.7341 L0.5265,110.8731 C-0.5445,114.1691 0.6285,117.7801 3.4325,119.8171 L105.0615,193.6551 L12.2685,74.7341 L12.2685,74.7341 Z" fill="#FCA326" class="tanuki-shape"></path>
-                            <path id="tanuki-right-eye"   d="M105.0614,193.6548 L66.4214,74.7338 L12.2684,74.7338 L105.0614,193.6548 L105.0614,193.6548 Z" fill="#FC6D26" class="tanuki-shape"></path>
-                            <path id="tanuki-nose"        d="M105.0614,193.655 L105.0614,193.655 L143.7014,74.734 L66.4214,74.734 L105.0614,193.655 L105.0614,193.655 Z" fill="#E24329" class="tanuki-shape"></path>
-                            <path id="tanuki-left-eye"    d="M105.0614,193.6548 L143.7014,74.7338 L197.8544,74.7338 L105.0614,193.6548 L105.0614,193.6548 Z" fill="#FC6D26" class="tanuki-shape"></path>
-                            <path id="tanuki-left-cheek"  d="M197.8544,74.7341 L197.8544,74.7341 L209.5964,110.8731 C210.6674,114.1691 209.4944,117.7801 206.6904,119.8171 L105.0614,193.6551 L197.8544,74.7341 L197.8544,74.7341 Z" fill="#FCA326" class="tanuki-shape"></path>
-                            <path id="tanuki-left-ear"    d="M197.8544,74.7342 L143.7014,74.7342 L166.9744,3.1092 C168.1714,-0.5768 173.3854,-0.5758 174.5824,3.1092 L197.8544,74.7342 L197.8544,74.7342 Z" fill="#E24329" class="tanuki-shape"></path>
-                        </g>
-                    </g>
-                </g>
-            </g>
-        </g>
-    </g>
+<svg width="36" height="36" id="tanuki-logo">
+  <path id="tanuki-right-ear" class="tanuki-shape" fill="#e24329" d="M2 14l9.38 9v-9l-4-12.28c-.205-.632-1.176-.632-1.38 0z"/>
+  <path id="tanuki-left-ear" class="tanuki-shape" fill="#e24329" d="M34 14l-9.38 9v-9l4-12.28c.205-.632 1.176-.632 1.38 0z"/>
+  <path id="tanuki-nose" class="tanuki-shape" fill="#e24329" d="M18,34.38 3,14 33,14 Z"/>
+  <path id="tanuki-right-eye" class="tanuki-shape" fill="#fc6d26" d="M18,34.38 11.38,14 2,14 6,25Z"/>
+  <path id="tanuki-left-eye" class="tanuki-shape" fill="#fc6d26" d="M18,34.38 24.62,14 34,14 30,25Z"/>
+  <path id="tanuki-right-cheek" class="tanuki-shape" fill="#fca326" d="M2 14L.1 20.16c-.18.565 0 1.2.5 1.56l17.42 12.66z"/>
+  <path id="tanuki-left-cheek" class="tanuki-shape" fill="#fca326" d="M34 14l1.9 6.16c.18.565 0 1.2-.5 1.56L18 34.38z"/>
 </svg>