minor symfony#20613 [Filesystem] Remove extra argv from dumpFile() calls in tests (chalasr)

This PR was submitted for the master branch but it was merged into the 3.1 branch instead (closes symfony#20613).

Discussion
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[Filesystem] Remove extra argv from dumpFile() calls in tests

| Q             | A
| ------------- | ---
| Branch?       | master
| Tests pass?   | yes
| License       | MIT

Commits
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1b298e5 [Filesystem] Remove extra argv in dumpFile() tests

Author: fabpot

src/Symfony/Component/Filesystem/Tests/FilesystemTest.php

@@ -1139,7 +1139,7 @@ public function testDumpFileWithFileScheme()
         $scheme = 'file://';
         $filename = $scheme.$this->workspace.DIRECTORY_SEPARATOR.'foo'.DIRECTORY_SEPARATOR.'baz.txt';
 
-        $this->filesystem->dumpFile($filename, 'bar', null);
+        $this->filesystem->dumpFile($filename, 'bar');
 
         $this->assertFileExists($filename);
         $this->assertSame('bar', file_get_contents($filename));
@@ -1150,7 +1150,7 @@ public function testDumpFileWithZlibScheme()
         $scheme = 'compress.zlib://';
         $filename = $this->workspace.DIRECTORY_SEPARATOR.'foo'.DIRECTORY_SEPARATOR.'baz.txt';
 
-        $this->filesystem->dumpFile($filename, 'bar', null);
+        $this->filesystem->dumpFile($filename, 'bar');
 
         // Zlib stat uses file:// wrapper so remove scheme
         $this->assertFileExists(str_replace($scheme, '', $filename));