Compiler's method getContent() does not pass $file parameter to any filter

[MartinPavlik]

This causes that cssUrlsFilter does not work.

I believe, the problem is here: Compiler line 168

I use following fix that works fine for me:

    /**
     * Get joined content of all files
     * @param array $files
     * @return string
     */
    public function getContent(array $files = null)
    {
        if ($files === null) {
            $files = $this->collection->getFiles();
        }
        // load content
        $result = '';
        foreach ($files as $file) {
            $fileContent = PHP_EOL . $this->loadFile($file);
            foreach($this->filters as $filter) {
                $fileContent = call_user_func($filter, $fileContent, $this, $file);
            }
            $result .= $fileContent;
        }
        return $result;
    }

I can create a pull request, but I can't pass tests due to:

1) WebLoader\Test\CompilerTest::testGeneratingAndFilters
Failed asserting that two strings are equal.
--- Expected
+++ Actual
@@ @@
 '-
-a:cba,
-b:fed,
+a:cba,-
+a:cba,-
+b:fed,-
+b:fed,-
 c:ihg,-
-a:cba,
-b:fed,
 c:ihg,'

https://forum.nette.org/cs/2578-addon-webloader-extras-webloader?p=7#p165520

@janmarek