Fix input type inference when type=>checkbox

FormHelper should not infer types when the explicit type is checkbox.
Instead the provided type should be used.

Fixes #2491

lib/Cake/Test/Case/View/Helper/FormHelperTest.php

@@ -2851,6 +2851,34 @@ public function testInputOverridingMagicSelectType() {
 		$this->assertTags($result, $expected);
 	}
 
+/**
+ * Test that inferred types do not override developer input
+ *
+ * @return void
+ */
+	public function testInputMagicTypeDoesNotOverride() {
+		$this->View->viewVars['users'] = array('value' => 'good', 'other' => 'bad');
+		$result = $this->Form->input('Model.user', array('type' => 'checkbox'));
+		$expected = array(
+			'div' => array('class' => 'input checkbox'),
+			array('input' => array(
+				'type' => 'hidden',
+				'name' => 'data[Model][user]',
+				'id' => 'ModelUser_',
+				'value' => 0,
+			)),
+			array('input' => array(
+				'name' => 'data[Model][user]',
+				'type' => 'checkbox',
+				'id' => 'ModelUser',
+				'value' => 1
+			)),
+			'label' => array('for' => 'ModelUser'), 'User', '/label',
+			'/div'
+		);
+		$this->assertTags($result, $expected);
+	}
+
 /**
  * Test that magic input() selects are created for type=number
  *

lib/Cake/View/Helper/FormHelper.php

@@ -1082,7 +1082,7 @@ protected function _parseOptions($options) {
 			$options = $this->_magicOptions($options);
 		}
 
-		if (in_array($options['type'], array('checkbox', 'radio', 'select'))) {
+		if (in_array($options['type'], array('radio', 'select'))) {
 			$options = $this->_optionsOptions($options);
 		}