Bump required PHP version to 5.5.9

Result of RfC and extensive discussion. RfC approved
by Tim/ArchCom on 2016-01-27.

Bug: T75901
Depends-On: I00e2e7adf5202384fc92371b8d0551782c3c17cb
Change-Id: I68c5b5d60952418ff8300c163edfe2275571f41f

Author: Chad Horohoe

.travis.yml

@@ -12,9 +12,9 @@ matrix:
   fast_finish: true
   include:
     - env: dbtype=mysql
-      php: 5.3
+      php: 5.5
     - env: dbtype=postgres
-      php: 5.3
+      php: 5.5
     - env: dbtype=mysql
       php: hhvm
     - env: dbtype=mysql

INSTALL

@@ -6,7 +6,7 @@ Starting with MediaWiki 1.2.0, it's possible to install and configure the wiki
 "in-place", as long as you have the necessary prerequisites available.
 
 Required software:
-* Web server with PHP 5.3.3 or higher.
+* Web server with PHP 5.5.9 or higher.
 * A SQL server, the following types are supported
 ** MySQL 5.0.3 or higher
 ** PostgreSQL 8.3 or higher

RELEASE-NOTES-1.27

@@ -8,6 +8,10 @@ THIS IS NOT A RELEASE YET
 MediaWiki 1.27 is an alpha-quality branch and is not recommended for use in
 production.
 
+=== PHP version requirement ===
+As of 1.27, MediaWiki now requires PHP 5.5.9 or higher. This corresponds with
+HHVM 3.1.
+
 === Configuration changes in 1.27 ===
 * $wgUseLinkNamespaceDBFields was removed.
 * Deprecated $wgResourceLoaderMinifierStatementsOnOwnLine and
@@ -314,7 +318,7 @@ changes to languages because of Phabricator reports.
 
 == Compatibility ==
 
-MediaWiki 1.27 requires PHP 5.3.3 or later. There is experimental support for
+MediaWiki 1.27 requires PHP 5.5.9 or later. There is experimental support for
 HHVM 3.6.5 or later.
 
 MySQL is the recommended DBMS. PostgreSQL or SQLite can also be used, but

composer.json

@@ -23,7 +23,7 @@
 		"mediawiki/at-ease": "1.1.0",
 		"oojs/oojs-ui": "0.15.2",
 		"oyejorge/less.php": "1.7.0.10",
-		"php": ">=5.3.3",
+		"php": ">=5.5.9",
 		"psr/log": "1.0.0",
 		"wikimedia/assert": "0.2.2",
 		"wikimedia/base-convert": "1.0.1",

includes/PHPVersionCheck.php

@@ -31,7 +31,7 @@
  */
 function wfEntryPointCheck( $entryPoint ) {
 	$mwVersion = '1.27';
-	$minimumVersionPHP = '5.3.3';
+	$minimumVersionPHP = '5.5.9';
 	$phpVersion = PHP_VERSION;
 
 	if ( !function_exists( 'version_compare' )