Don't ltrim when preserving formatting

We shouldn't ltrim when printing a whole file, that way we will
not just fail to preserve formatting, but actually change semantics
by dropping meaningful whitespace.

lib/PhpParser/PrettyPrinterAbstract.php

@@ -540,7 +540,7 @@ abstract class PrettyPrinterAbstract implements PrettyPrinter {
             $result = "<?php\n" . $this->pStmts($stmts, false);
         }
 
-        return ltrim($this->handleMagicTokens($result));
+        return $this->handleMagicTokens($result);
     }
 
     protected function pFallback(Node $node, int $precedence, int $lhsPrecedence): string {

test/code/formatPreservation/inlineHtml.test

@@ -110,3 +110,13 @@ function test()
     foo();
     baz();
 }
+-----
+
+
+<?php $x;
+-----
+/* Do nothing, but make sure leading newlines are preserved. */
+-----
+
+
+<?php $x;