[clang-format] Don't test stability if JS format test fails (#136662)

clang/unittests/Format/FormatTestJS.cpp

diff --git a/clang/unittests/Format/FormatTestJS.cpp b/clang/unittests/Format/FormatTestJS.cpp
index 1cfacc0..91577b9a 100644
--- a/clang/unittests/Format/FormatTestJS.cpp
+++ b/clang/unittests/Format/FormatTestJS.cpp
@@ -48,18 +48,22 @@
   static void verifyFormat(
       StringRef Code,
       const FormatStyle &Style = getGoogleStyle(FormatStyle::LK_JavaScript)) {
-    EXPECT_EQ(Code.str(), format(Code, Style)) << "Expected code is not stable";
-    std::string Result = format(test::messUp(Code), Style);
-    EXPECT_EQ(Code.str(), Result) << "Formatted:\n" << Result;
+    auto Result = format(test::messUp(Code), Style);
+    EXPECT_EQ(Code, Result) << "Formatted:\n" << Result;
+    if (Code != Result)
+      return;
+    EXPECT_EQ(Code, format(Code, Style)) << "Expected code is not stable";
   }
 
   static void verifyFormat(
       StringRef Expected, StringRef Code,
       const FormatStyle &Style = getGoogleStyle(FormatStyle::LK_JavaScript)) {
-    EXPECT_EQ(Expected.str(), format(Expected, Style))
+    auto Result = format(Code, Style);
+    EXPECT_EQ(Expected, Result) << "Formatted:\n" << Result;
+    if (Expected != Result)
+      return;
+    EXPECT_EQ(Expected, format(Expected, Style))
         << "Expected code is not stable";
-    std::string Result = format(Code, Style);
-    EXPECT_EQ(Expected.str(), Result) << "Formatted:\n" << Result;
   }
 };