clang-format: [JS] don't sort named imports if off.

[mprobst]

Summary

The previous implementation would accidentally still sort the individual
named imports, even if the module reference was in a clang-format off
block.

clang/lib/Format/SortJavaScriptImports.cpp

while (Reference != References.end()) {
       PreviousReference->SymbolsMerged = true;
       // Remove the merged import.
       Reference = References.erase(Reference);
     }
   }
 
   // Appends ``Reference`` to ``Buffer``.
   void appendReference(std::string &Buffer, JsModuleReference &Reference) {
+    if (Reference.FormattingOff) {
+      Buffer +=
+          getSourceText(Reference.Range.getBegin(), Reference.Range.getEnd());
+      return;
+    }
     // Sort the individual symbols within the import.
     // E.g. `import {b, a} from 'x';` -> `import {a, b} from 'x';`
     SmallVector<JsImportedSymbol, 1> Symbols = Reference.Symbols;
     llvm::stable_sort(
         Symbols, [&](const JsImportedSymbol &LHS, const JsImportedSymbol &RHS) {
           return LHS.Symbol.compare_lower(RHS.Symbol) < 0;
         });
     if (!Reference.SymbolsMerged && Symbols == Reference.Symbols) {

clang/unittests/Format/SortImportsTestJS.cpp

verifySort("// clang-format on\n"
              "// clang-format off\n",
              "// clang-format on\n"
              "import {C} from './c';\n"
              "import {B} from './b';\n"
              "import {A} from './a';\n"
              "// clang-format off\n");
 }
 
+TEST_F(SortImportsTestJS, RespectsClangFormatOffInNamedImports) {
+  verifySort("// clang-format off\n"
+             "import {B, A} from './b';\n"
+             "// clang-format on\n"
+             "const x = 1;",
+             "// clang-format off\n"
+             "import {B, A} from './b';\n"
+             "// clang-format on\n"
+             "const x =   1;");
+}
+
 } // end namespace
 } // end namespace format
 } // end namespace clang