fix (md-dialog)

Only append an md-theme attribute if the md-dialog is propagated from an element that contains an md-theme.

Issue: #10276

Author: Cody Mikol

src/components/dialog/dialog.js

@@ -693,7 +693,8 @@ function MdDialogProvider($$interimElementProvider) {
         var startSymbol = $interpolate.startSymbol();
         var endSymbol = $interpolate.endSymbol();
         var theme = startSymbol + (options.themeWatch ? '' : '::') + 'theme' + endSymbol;
-        return '<div class="md-dialog-container" tabindex="-1" md-theme="' + theme + '">' + validatedTemplate(template) + '</div>';
+        var themeAttr = (options.hasTheme) ? 'md-theme="'+theme+'"': '';
+        return '<div class="md-dialog-container" tabindex="-1" ' + themeAttr + '>' + validatedTemplate(template) + '</div>';
 
         /**
          * The specified template should contain a <md-dialog> wrapper element....
@@ -854,7 +855,9 @@ function MdDialogProvider($$interimElementProvider) {
 
       var themeCtrl = targetEl && targetEl.controller('mdTheme');
 
-      if (!themeCtrl) {
+      options.hasTheme = (!!themeCtrl);
+
+      if (!options.hasTheme) {
         return;
       }