Fix a "continue;" inside a switch in ArcanistPHPCompatibilityXHPASTLinterRule

Summary: See <https://discourse.phabricator-community.org/t/arc-diff-fails-on-incompatible-linter-rule-with-php7-3/2198>.

Test Plan: Looked at the code carefully.

Reviewers: amckinley

Reviewed By: amckinley

Differential Revision: https://secure.phabricator.com/D19868

src/lint/linter/xhpast/rules/ArcanistPHPCompatibilityXHPASTLinterRule.php

@@ -70,7 +70,7 @@ final class ArcanistPHPCompatibilityXHPASTLinterRule
           $symbol = $params->getChildByIndex(0);
 
           if (!$symbol->isStaticScalar()) {
-            continue;
+            break;
           }
 
           $symbol_name = $symbol->evalStatic();