Simplify how fullBase is calculated.

Using FULL_BASE_URL fixes URL generation when URL rewriting is
disabled.

Fixes #3777

lib/Cake/Test/Case/View/HelperTest.php

@@ -658,6 +658,21 @@ public function testAssetUrl() {
 		$this->assertEquals('foo.jpg?one=two&three=four', $result);
 	}
 
+/**
+ * Test assetUrl with no rewriting.
+ *
+ * @return void
+ */
+	public function testAssetUrlNoRewrite() {
+		$this->Helper->request->addPaths(array(
+			'base' => '/cake_dev/index.php',
+			'webroot' => '/cake_dev/app/webroot/',
+			'here' => '/cake_dev/index.php/tasks',
+		));
+		$result = $this->Helper->assetUrl('img/cake.icon.png', array('fullBase' => true));
+		$this->assertEquals('http://localhost/cake_dev/app/webroot/img/cake.icon.png', $result);
+	}
+
 /**
  * Test assetUrl with plugins.
  *

lib/Cake/View/Helper.php

@@ -328,12 +328,7 @@ public function assetUrl($path, $options = array()) {
 		$path = $this->_encodeUrl($this->assetTimestamp($this->webroot($path)));
 
 		if (!empty($options['fullBase'])) {
-			$base = $this->url('/', true);
-			$len = strlen($this->request->webroot);
-			if ($len) {
-				$base = substr($base, 0, -$len);
-			}
-			$path = $base . $path;
+			$path = rtrim(FULL_BASE_URL, '/') . '/' . ltrim($path, '/');
 		}
 		return $path;
 	}