FIX: properly support HTTPS CDN on HTTP site

Previously we changed all CDN links to schemaless.

This is desirable for non HTTPS sites, to ease migration to HTTPS.
It is not desirable for secure sites.

Once site is secure or CDN is secure a rebake should be required
to move it back to non-secure.

lib/url_helper.rb

@@ -18,7 +18,7 @@ class UrlHelper
   end
 
   def self.schemaless(url)
-    url.sub(/^https?:/, "")
+    url.sub(/^http:/, "")
   end
 
 end

spec/components/cooked_post_processor_spec.rb

@@ -317,7 +317,7 @@ describe CookedPostProcessor do
 
     context "when CDN is enabled" do
 
-      it "uses schemaless CDN url for uploads" do
+      it "does use schemaless CDN url for http uploads" do
         Rails.configuration.action_controller.stubs(:asset_host).returns("http://my.cdn.com")
         cpp.optimize_urls
         expect(cpp.html).to match_html '<a href="//my.cdn.com/uploads/default/2/2345678901234567.jpg">Link</a>
@@ -325,6 +325,14 @@ describe CookedPostProcessor do
        <img src="http://foo.bar/image.png">'
       end
 
+      it "does not use schemaless CDN url for https uploads" do
+        Rails.configuration.action_controller.stubs(:asset_host).returns("https://my.cdn.com")
+        cpp.optimize_urls
+        expect(cpp.html).to match_html '<a href="https://my.cdn.com/uploads/default/2/2345678901234567.jpg">Link</a>
+       <img src="https://my.cdn.com/uploads/default/1/1234567890123456.jpg"><a href="http://www.google.com">Google</a>
+       <img src="http://foo.bar/image.png">'
+      end
+
     end
 
   end

spec/components/url_helper_spec.rb

@@ -56,9 +56,9 @@ describe UrlHelper do
 
   describe "#schemaless" do
 
-    it "removes http or https schemas only" do
+    it "removes http schemas only" do
       expect(UrlHelper.schemaless("http://www.discourse.org")).to eq("//www.discourse.org")
-      expect(UrlHelper.schemaless("https://secure.discourse.org")).to eq("//secure.discourse.org")
+      expect(UrlHelper.schemaless("https://secure.discourse.org")).to eq("https://secure.discourse.org")
       expect(UrlHelper.schemaless("ftp://ftp.discourse.org")).to eq("ftp://ftp.discourse.org")
     end