fix: attribute in data inspector values are difficult to read in dark mode, fixes vuejs#985

Author: Guillaume Chau

shells/dev/target/NativeTypes.vue

@@ -12,6 +12,11 @@
 
     <TestComponent ref="component" />
 
+    <div
+      id="aDiv"
+      ref="someDiv"
+    />
+
     <p>
       <button @click="sendComponent()">
         Vuex mutation

src/devtools/components/DataField.vue

@@ -660,6 +660,9 @@ export default {
         opacity 0.5
       >>> .attr-title
         color #800080
+        .vue-ui-dark-mode &
+          color #e36eec
+
   .vue-ui-dark-mode &
     color #bdc6cf
     &.string, &.native