Fix local handle leak in RegExpStringModificationTest.

test/cctest/test-api.cc

Index: test/cctest/test-api.cc
diff --git a/test/cctest/test-api.cc b/test/cctest/test-api.cc
index 8bfa51c60a9ea81543ea20200eac52581241063f..adaf102704768fb35279423474dcc7d89a0f7f7a 100644
--- a/test/cctest/test-api.cc
+++ b/test/cctest/test-api.cc
@@ -9203,6 +9203,7 @@ class RegExpStringModificationTest {
            morphs_ < kMaxModifications) {
       int morphs_before = morphs_;
       {
+        v8::HandleScope scope;
         // Match 15-30 "a"'s against 14 and a "b".
         const char* c_source =
             "/a?a?a?a?a?a?a?a?a?a?a?a?a?a?aaaaaaaaaaaaaaaa/"