Add dark theme support for coverage button

plugins/c9.ide.layout.classic/themes/default-dark-gray.less

@@ -1683,4 +1683,6 @@
 @stats-menu-graph-color: @stats-button-progress-highlight-hover-color;
 @stats-menu-info-background: rgba(255, 255, 255, 0.07);
 @stats-menu-info-border: 1px solid rgba(0, 0, 0, 0.4);
-@stats-menu-info-box-shadow: 1px 1px rgba(255,255,255,0.06), inset 1px 1px rgba(255,255,255,0.06);
+@stats-menu-info-box-shadow: 1px 1px rgba(255,255,255,0.06), inset 1px 1px rgba(255,255,255,0.06);
+
+@coverage-button-font-size: 14px;

plugins/c9.ide.layout.classic/themes/default-dark.less

@@ -1684,3 +1684,5 @@
 @stats-menu-info-background: rgba(255, 255, 255, 0.07);
 @stats-menu-info-border: 1px solid rgba(0, 0, 0, 0.4);
 @stats-menu-info-box-shadow: 1px 1px rgba(255,255,255,0.06), inset 1px 1px rgba(255,255,255,0.06);
+
+@coverage-button-font-size: 14px;

plugins/c9.ide.layout.classic/themes/default-flat-light.less

@@ -1683,4 +1683,6 @@
 @stats-menu-graph-color: #8ED6FF;
 @stats-menu-info-background: #F9F9F9;
 @stats-menu-info-border: 0;
-@stats-menu-info-box-shadow: none;
+@stats-menu-info-box-shadow: none;
+
+@coverage-button-font-size: 25px;

plugins/c9.ide.layout.classic/themes/default-light-gray.less

@@ -1683,4 +1683,6 @@
 @stats-menu-graph-color: #8ED6FF;
 @stats-menu-info-background: #F9F9F9;
 @stats-menu-info-border: 0;
-@stats-menu-info-box-shadow: none;
+@stats-menu-info-box-shadow: none;
+
+@coverage-button-font-size: 14px;

plugins/c9.ide.layout.classic/themes/default-light.less

@@ -1683,4 +1683,6 @@
 @stats-menu-graph-color: #8ED6FF;
 @stats-menu-info-background: #F9F9F9;
 @stats-menu-info-border: 0;
-@stats-menu-info-box-shadow: none;
+@stats-menu-info-box-shadow: none;
+
+@coverage-button-font-size: 14px;