HttpProvider: CORS issue with Firefox and Safari (web3#3112)

* CORS error fixed

Author: nivida

CHANGELOG.md

@@ -65,3 +65,4 @@ Released with 1.0.0-beta.37 code base.
 - Fix incorrectly populating chainId param with `net_version` when signing txs (#2378)
 - regeneratorRuntime error fixed (#3058)
 - Fix accessing event.name where event is undefined (#3014)
+- HttpProvider: CORS issue with Firefox and Safari (#2978)

dist/web3.min.js

@@ -23,7 +23,7 @@
  */
 
 var errors = require('web3-core-helpers').errors;
-var XHR2 = require('xhr2-cookies').XMLHttpRequest // jshint ignore: line
+var XHR2 = require('xhr2-cookies').XMLHttpRequest; // jshint ignore: line
 var http = require('http');
 var https = require('https');
 
@@ -34,32 +34,38 @@ var https = require('https');
 var HttpProvider = function HttpProvider(host, options) {
     options = options || {};
 
-    var keepAlive =
-        (options.keepAlive === true || options.keepAlive !== false) ?
-            true :
-            false;
+    var keepAlive = (options.keepAlive === true || options.keepAlive !== false) ? true : false;
     this.host = host || 'http://localhost:8545';
     if (this.host.substring(0,5) === "https") {
         this.httpsAgent = new https.Agent({ keepAlive: keepAlive });
-    }else{
+    } else {
         this.httpAgent = new http.Agent({ keepAlive: keepAlive });
     }
+
+    this.withCredentials = options.withCredentials || false;
     this.timeout = options.timeout || 0;
     this.headers = options.headers;
     this.connected = false;
 };
 
 HttpProvider.prototype._prepareRequest = function(){
-    var request = new XHR2();
-    request.nodejsSet({
-        httpsAgent:this.httpsAgent,
-        httpAgent:this.httpAgent
-    });
+    var request;
+
+    // the current runtime is a browser
+    if (typeof XMLHttpRequest !== 'undefined') {
+        request = new XMLHttpRequest();
+    } else {
+        request = new XHR2();
+        request.nodejsSet({
+            httpsAgent:this.httpsAgent,
+            httpAgent:this.httpAgent
+        });
+    }
 
     request.open('POST', this.host, true);
     request.setRequestHeader('Content-Type','application/json');
-    request.timeout = this.timeout && this.timeout !== 1 ? this.timeout : 0;
-    request.withCredentials = true;
+    request.timeout = this.timeout;
+    request.withCredentials = this.withCredentials;
 
     if(this.headers) {
         this.headers.forEach(function(header) {