fix(lumo): make icon theme respect tertiary-inline (#134)

Author: web-padawan

test/visual/icons.html

@@ -65,4 +65,8 @@ <h2>Icons and size presets</h2>
     <span>Icon suffix</span>
     <iron-icon slot="suffix" icon="lumo:arrow-right"></iron-icon>
   </vaadin-button>
+
+  <vaadin-button theme="icon tertiary-inline">
+    <iron-icon icon="lumo:edit"></iron-icon>
+  </vaadin-button>
 </body>

test/visual/screens/vaadin-button/icons-lumo/default/chrome.png

@@ -256,7 +256,7 @@
 
       /* Icon-only */
 
-      :host([theme~="icon"]) {
+      :host([theme~="icon"]:not([theme~="tertiary-inline"])) {
         min-width: var(--lumo-button-size);
         padding-left: calc(var(--lumo-button-size) / 4);
         padding-right: calc(var(--lumo-button-size) / 4);