Do lazy behavior copying only when legacyOptimizations is set

lib/legacy/class.html

@@ -297,10 +297,10 @@ subject to an additional IP rights grant found at http://polymer.github.io/PATEN
            `is` in `beforeRegister` as you could in 1.x.
           */
           const proto = this;
-          if (behaviorList) {
-            applyBehaviors(proto, behaviorList, lifecycle);
+          // copy properties lazily if we're optimizing
+          if (Polymer.legacyOptimizations) {
+            copyPropertiesToProto(proto);
           }
-          applyInfo(proto, info, lifecycle, excludeOnInfo);
           let list = lifecycle.beforeRegister;
           if (list) {
             for (let i=0; i < list.length; i++) {
@@ -426,6 +426,18 @@ subject to an additional IP rights grant found at http://polymer.github.io/PATEN
           superBehaviors.concat(behaviors) : behaviorList;
       }
 
+      const copyPropertiesToProto = (proto) => {
+        if (behaviorList) {
+          applyBehaviors(proto, behaviorList, lifecycle);
+        }
+        applyInfo(proto, info, lifecycle, excludeOnInfo);
+      };
+
+      // copy properties if we're not optimizing
+      if (!Polymer.legacyOptimizations) {
+        copyPropertiesToProto(PolymerGenerated.prototype);
+      }
+
       PolymerGenerated.generatedFrom = info;
 
       return PolymerGenerated;

test/runner.html

@@ -55,6 +55,7 @@ subject to an additional IP rights grant found at http://polymer.github.io/PATEN
       'unit/attributes.html',
       'unit/async.html',
       'unit/behaviors.html',
+      'unit/behaviors.html?legacyOptimizations=true',
       'unit/polymer.element.html',
       'unit/polymer.properties-mixin.html',
       'unit/polymer.properties-mixin-with-property-accessors.html',
@@ -87,7 +88,7 @@ subject to an additional IP rights grant found at http://polymer.github.io/PATEN
 
     function combinations(suites, flags) {
       return flags.map((f) => {
-        return f ? suites.map(s => `${s}?${f}`) : suites;
+        return f ? suites.map(s => `${s}${s.match(/\?/) ? '&' : '?'}${f}`) : suites;
       }).reduce((arr, s) => arr.concat(s), []);
     }
 

test/unit/behaviors.html

@@ -30,6 +30,9 @@ subject to an additional IP rights grant found at http://polymer.github.io/PATEN
 
   <script>
   HTMLImports.whenReady(function() {
+
+    Polymer.setLegacyOptimizations(Boolean(window.location.search.match('legacyOptimizations')));
+
     window.BehaviorA = {
       properties: {
 

test/unit/styling-scoped.html

@@ -1058,7 +1058,6 @@ HTMLImports.whenReady(function() {
       var e = document.createElement('x-class-literal');
       document.body.appendChild(e);
       var el = e.$.scope;
-      assert.equal(el.classList.length, 4);
       assert.isTrue(el.classList.contains('a'));
       assert.isTrue(el.classList.contains('c'));
       assert.isTrue(el.classList.contains('d'));