[RGT][TextAPI] Remove a zero-trip loop and the assertions within it

[probinson]

Summary

Found by the Rotten Green Tests project.

[cishida]

Thank you!

llvm/unittests/TextAPI/TextStubV4Tests.cpp

TEST(TBDv4, ReadMultipleDocuments) {
   EXPECT_TRUE(File->isApplicationExtensionSafe());
   EXPECT_FALSE(File->isInstallAPI());
   EXPECT_EQ(PackedVersion(1, 0, 0), File->getCurrentVersion());
   EXPECT_EQ(PackedVersion(1, 0, 0), File->getCompatibilityVersion());
   InterfaceFileRef reexport("/System/Library/Frameworks/A.framework/A",
                             {Targets[0], Targets[2]});
   EXPECT_EQ(1U, File->reexportedLibraries().size());
   EXPECT_EQ(reexport, File->reexportedLibraries().front());
-  ExportedSymbolSeq Exports;
-  for (const auto *Sym : File->symbols()) {
-    EXPECT_FALSE(Sym->isWeakReferenced());
-    EXPECT_FALSE(Sym->isUndefined());
-    Exports.emplace_back(ExportedSymbol{Sym->getKind(), Sym->getName().str(),
-                                        Sym->isWeakDefined(),
-                                        Sym->isThreadLocalValue()});
-  }
-  EXPECT_EQ(0U, Exports.size());
+  EXPECT_TRUE(File->symbols().empty());
 
   // Check Inlined Document
-  Exports.clear();
   Targets.clear();
   Uuids.clear();
   PlatformKind Platform = PlatformKind::macOS;
   for (auto &&Arch : Archs)
     Targets.emplace_back(Target(Arch, Platform));
   Uuids = {
       {Targets[0], "20000000-0000-0000-0000-000000000000"},
       {Targets[1], "21111111-1111-1111-1111-111111111111"},
EXPECT_EQ(std::string("/System/Library/Frameworks/A.framework/A"),
             Document->getInstallName());
   EXPECT_EQ(PackedVersion(1, 2, 3), Document->getCurrentVersion());
   EXPECT_EQ(PackedVersion(1, 2, 0), Document->getCompatibilityVersion());
   EXPECT_EQ(5U, Document->getSwiftABIVersion());
   EXPECT_FALSE(Document->isTwoLevelNamespace());
   EXPECT_TRUE(Document->isApplicationExtensionSafe());
   EXPECT_FALSE(Document->isInstallAPI());
 
+  ExportedSymbolSeq Exports;
   ExportedSymbolSeq Reexports, Undefineds;
   for (const auto *Sym : Document->symbols()) {
     ExportedSymbol Temp =
         ExportedSymbol{Sym->getKind(), std::string(Sym->getName()),
                        Sym->isWeakDefined(), Sym->isThreadLocalValue()};
     EXPECT_FALSE(Sym->isWeakReferenced());
     if (Sym->isUndefined())
       Undefineds.emplace_back(std::move(Temp));