Turn on eslint rule one-var and fix existing errors.

tracing/tracing/base/quad.html

Index: tracing/tracing/base/quad.html
diff --git a/tracing/tracing/base/quad.html b/tracing/tracing/base/quad.html
index 9e66c5e21c5ffbac7061752a2e9b9ab3453989ee..7c0961eed2f428697294dd3e0d68a50663b96cb7 100644
--- a/tracing/tracing/base/quad.html
+++ b/tracing/tracing/base/quad.html
@@ -148,7 +148,10 @@ tr.exportTo('tr.b', function() {
       var v14 = tmpVec2s[1];
       var v23 = tmpVec2s[2];
       var v43 = tmpVec2s[3];
-      var l12, l14, l23, l43;
+      var l12;
+      var l14;
+      var l23;
+      var l43;
 
       vec2.sub(v12, this.p2, this.p1);
       l12 = vec2.length(v12);