Disable native JSON support for MariaDB 10.2.x

Since the JSON type is simply an alias to a LONG TEXT we must force
a comment, otherwise things will not work properly.

Also the test for JSON types should work regardless of native JSON
support (DBAL should add a comment to identify the correct type).

lib/Doctrine/DBAL/Platforms/MariaDb1027Platform.php

@@ -36,7 +36,7 @@ final class MariaDb1027Platform extends MySqlPlatform
      */
     public function hasNativeJsonType() : bool
     {
-        return true;
+        return false;
     }
 
     /**

tests/Doctrine/Tests/DBAL/Functional/Schema/MySqlSchemaManagerTest.php

@@ -12,12 +12,11 @@ use Doctrine\Tests\Types\MySqlPointType;
 
 class MySqlSchemaManagerTest extends SchemaManagerFunctionalTestCase
 {
-
     protected function setUp()
     {
         parent::setUp();
 
-        if (!Type::hasType('point')) {
+        if ( ! Type::hasType('point')) {
             Type::addType('point', MySqlPointType::class);
         }
     }
@@ -337,11 +336,6 @@ class MySqlSchemaManagerTest extends SchemaManagerFunctionalTestCase
 
     public function testJsonColumnType() : void
     {
-        $platform = $this->_sm->getDatabasePlatform();
-        if ( ! $platform->hasNativeJsonType()) {
-            $this->markTestSkipped("Requires native JSON type");
-        }
-
         $table = new Table('test_mysql_json');
         $table->addColumn('col_json', 'json');
         $this->_sm->dropAndCreateTable($table);

tests/Doctrine/Tests/DBAL/Platforms/MariaDb1027PlatformTest.php

@@ -19,7 +19,7 @@ class MariaDb1027PlatformTest extends AbstractMySQLPlatformTestCase
 
     public function testHasNativeJsonType() : void
     {
-        self::assertTrue($this->_platform->hasNativeJsonType());
+        self::assertFalse($this->_platform->hasNativeJsonType());
     }
 
     /**