Disable auto strip-whitespace on template with legacyOptimizations

2.x version of #5470

Author: dfreedm

lib/mixins/template-stamp.html

@@ -204,7 +204,7 @@
         if (!template._templateInfo) {
           let templateInfo = template._templateInfo = {};
           templateInfo.nodeInfoList = [];
-          templateInfo.stripWhiteSpace = Polymer.legacyOptimizations ||
+          templateInfo.stripWhiteSpace =
             (outerTemplateInfo && outerTemplateInfo.stripWhiteSpace) ||
             template.hasAttribute('strip-whitespace');
           this._parseTemplateContent(template, templateInfo, {parent: null});