fix(base href): always create absolute URLS in widgets

Every time we generate a link, much like every time we update the url
bar, we should update with an absolute url to avoid the <base href>
being added.

fixes #970

src/lib/InstantSearch.js

@@ -108,10 +108,12 @@ Usage: instantsearch({
     if (this.urlSync) {
       let syncWidget = urlSyncWidget(this.urlSync);
       this._createURL = syncWidget.createURL.bind(syncWidget);
+      this._createAbsoluteURL = relative => this._createURL(relative, {absolute: true});
       this._onHistoryChange = syncWidget.onHistoryChange.bind(syncWidget);
       this.widgets.push(syncWidget);
     } else {
       this._createURL = defaultCreateURL;
+      this._createAbsoluteURL = defaultCreateURL;
       this._onHistoryChange = function() {};
     }
 
@@ -160,7 +162,7 @@ Usage: instantsearch({
         results,
         state,
         helper,
-        createURL: this._createURL
+        createURL: this._createAbsoluteURL
       });
     }, this);
     this.emit('render');
@@ -174,7 +176,7 @@ Usage: instantsearch({
           state,
           helper,
           templatesConfig,
-          createURL: this._createURL,
+          createURL: this._createAbsoluteURL,
           onHistoryChange: _onHistoryChange
         });
       }

src/lib/__tests__/InstantSearch-test.js

@@ -195,7 +195,7 @@ describe('InstantSearch lifecycle', () => {
           expect(widget.render.calledOnce).toBe(true, 'widget.render called once');
           expect(widget.render.args[0])
             .toEqual([{
-              createURL: search._createURL,
+              createURL: search._createAbsoluteURL,
               results,
               state: helper.state,
               helper,

src/lib/url-sync.js

@@ -80,7 +80,7 @@ function getFullURL(relative) {
   return getLocationOrigin() + window.location.pathname + relative;
 }
 
-// IE <= 11 has no location.origin
+// IE <= 11 has no location.origin or buggy
 function getLocationOrigin() {
   return `${window.location.protocol}//${window.location.hostname}${window.location.port ? ':' + window.location.port : ''}`;
 }
@@ -147,14 +147,15 @@ class URLSync {
 
   // External API's
 
-  createURL(state) {
+  createURL(state, {absolute}) {
     let currentQueryString = this.urlUtils.readUrl();
     let filteredState = state.filter(this.trackedParameters);
     let foreignConfig = algoliasearchHelper.url.getUnrecognizedParametersInQueryString(currentQueryString, {mapping: this.mapping});
     // Add instantsearch version to reconciliate old url with newer versions
     foreignConfig.is_v = majorVersionNumber;
+    const relative = this.urlUtils.createURL(algoliasearchHelper.url.getQueryStringFromState(filteredState, {mapping: this.mapping}));
 
-    return this.urlUtils.createURL(algoliasearchHelper.url.getQueryStringFromState(filteredState, {mapping: this.mapping}));
+    return absolute ? getFullURL(relative) : relative;
   }
 
   onHistoryChange(fn) {