Improved styling of scrollable tabs.

Scroll buttons are now better aligned with tab text, have the correct
Material Design icon colour, and tab text is better vertically centered.
Disabled scroll buttons also no longer cause hovering cursors to display
pointers.

resources/report/css/material.css

@@ -98,10 +98,15 @@ html /deep/ core-menu .core-selected {
 html /deep/ paper-tabs::shadow #selectionBar {
    height: 2px;
 }
+html /deep/ paper-tabs::shadow .scroll-button > paper-icon-button {
+    vertical-align: middle;
+    color: rgba(0, 0, 0, 0.54);
+}
 
 /* paper-tab */
 html /deep/ paper-tab::shadow .tab-content {
     text-transform: uppercase;
+    line-height: 48px;
 }
 
 /* core-drawer-panel */

resources/report/css/overrides.css

@@ -47,6 +47,11 @@ html /deep/ paper-tabs::shadow #selectionBar {
 html /deep/ paper-tab::shadow #ink {
     color: #64B5F6;
 }
+/* Set the paper tab scroll buttons so they don't cause the cursor to display as
+   as a pointer when they are disabled. */
+html /deep/ paper-tabs::shadow .scroll-button .hidden {
+    pointer-events: none;
+}
 /* Set the drawer z-index so that it doesn't appear below plugin cards. */
 core-drawer-panel::shadow #drawer {
     z-index: 1;