bug symfony#15248 Added 'default' color (jaytaph)

This PR was submitted for the 2.7 branch but it was merged into the 2.3 branch instead (closes symfony#15248).

Discussion
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Added 'default' color

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | symfony#15246
| License       | MIT
| Doc PR        |

Adding a "default" ansi color which corresponds to 39 and 49.

Commits
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c4bf2e6 Added 'default' color

Author: fabpot

src/Symfony/Component/Console/Formatter/OutputFormatterStyle.php

@@ -29,6 +29,7 @@ class OutputFormatterStyle implements OutputFormatterStyleInterface
         'magenta' => 35,
         'cyan' => 36,
         'white' => 37,
+        'default' => 39,
     );
     private static $availableBackgroundColors = array(
         'black' => 40,
@@ -39,6 +40,7 @@ class OutputFormatterStyle implements OutputFormatterStyleInterface
         'magenta' => 45,
         'cyan' => 46,
         'white' => 47,
+        'default' => 49,
     );
     private static $availableOptions = array(
         'bold' => 1,

src/Symfony/Component/Console/Tests/Formatter/OutputFormatterStyleTest.php

@@ -37,6 +37,9 @@ public function testForeground()
         $style->setForeground('blue');
         $this->assertEquals("\033[34mfoo\033[0m", $style->apply('foo'));
 
+        $style->setForeground('default');
+        $this->assertEquals("\033[39mfoo\033[39m", $style->apply('foo'));
+
         $this->setExpectedException('InvalidArgumentException');
         $style->setForeground('undefined-color');
     }
@@ -51,6 +54,9 @@ public function testBackground()
         $style->setBackground('yellow');
         $this->assertEquals("\033[43mfoo\033[0m", $style->apply('foo'));
 
+        $style->setBackground('default');
+        $this->assertEquals("\033[49mfoo\033[49m", $style->apply('foo'));
+
         $this->setExpectedException('InvalidArgumentException');
         $style->setBackground('undefined-color');
     }