[WebAssembly] Remove unneeded classifer methods from Symbol class. NFC.

[sbc100]

Summary

We already have isa<> for this, and these methods were simply
duplicating those redundantly.

Also remove asserts from Symbol.cpp that were truly redundant.

[ruiu]

LGTM

wasm/SymbolTable.cpp

 // For functions this can also involve verifying that the signatures match.
 static void checkSymbolTypes(const Symbol &Existing, const InputFile &F,
                              bool NewIsFunction, const WasmSignature *NewSig) {
   if (Existing.isLazy())
     return;
 
   // First check the symbol types match (i.e. either both are function
   // symbols or both are data symbols).
-  if (Existing.isFunction() != NewIsFunction) {
+  if (isa<FunctionSymbol>(Existing) != NewIsFunction) {
     error("symbol type mismatch: " + Existing.getName() + "\n>>> defined as " +
-          (Existing.isFunction() ? "Function" : "Global") + " in " +
+          (isa<FunctionSymbol>(Existing) ? "Function" : "Global") + " in " +
           toString(Existing.getFile()) + "\n>>> defined as " +
           (NewIsFunction ? "Function" : "Global") + " in " + F.getName());
     return;
   }
 
   // For function symbols, optionally check the function signature matches too.
   auto *ExistingFunc = dyn_cast<FunctionSymbol>(&Existing);
   if (!ExistingFunc || !Config->CheckSignatures)

wasm/Symbols.h

public:
   Kind kind() const { return SymbolKind; }
 
   bool isLazy() const { return SymbolKind == LazyKind; }
   bool isDefined() const { return SymbolKind <= LastDefinedKind; }
   bool isUndefined() const {
     return SymbolKind == UndefinedGlobalKind ||
            SymbolKind == UndefinedFunctionKind;
   }
-  bool isFunction() const {
-    return SymbolKind == DefinedFunctionKind ||
-           SymbolKind == UndefinedFunctionKind;
-  }
-  bool isGlobal() const { return !isFunction(); }
   bool isLocal() const;
   bool isWeak() const;
   bool isHidden() const;
 
   // Returns the symbol name.
   StringRef getName() const { return Name; }
 
   // Returns the file from which this symbol was created.

wasm/Symbols.cpp

if (auto *F = dyn_cast_or_null<InputFunction>(Chunk)) {
     return;
   }
   DEBUG(dbgs() << "setTableIndex " << Name << " -> " << Index << "\n");
   assert(TableIndex == INVALID_INDEX);
   TableIndex = Index;
 }
 
 uint32_t DefinedGlobal::getVirtualAddress() const {
-  assert(isGlobal());
   DEBUG(dbgs() << "getVirtualAddress: " << getName() << "\n");
   return Chunk ? dyn_cast<InputSegment>(Chunk)->translateVA(VirtualAddress)
                : VirtualAddress;
 }
 
 void DefinedGlobal::setVirtualAddress(uint32_t Value) {
   DEBUG(dbgs() << "setVirtualAddress " << Name << " -> " << Value << "\n");
-  assert(isGlobal());
   VirtualAddress = Value;
 }
 
 std::string lld::toString(const wasm::Symbol &Sym) {
   if (Config->Demangle)
     if (Optional<std::string> S = demangleItanium(Sym.getName()))
       return "`" + *S + "'";
   return Sym.getName();

wasm/Writer.cpp

if (ExportMemory) {
     writeExport(OS, MemoryExport);
   }
 
   for (const WasmExportEntry &E : ExportedSymbols) {
     DEBUG(dbgs() << "Export: " << E.Sym->getName() << "\n");
     WasmExport Export;
     Export.Name = E.FieldName;
     Export.Index = E.Sym->getOutputIndex();
-    if (E.Sym->isFunction())
+    if (isa<FunctionSymbol>(E.Sym))
       Export.Kind = WASM_EXTERNAL_FUNCTION;
     else
       Export.Kind = WASM_EXTERNAL_GLOBAL;
     writeExport(OS, Export);
   }
 }
 
 void Writer::createStartSection() {}
void Writer::calculateExports() {
   if (WasmSym::CallCtors && (!WasmSym::CallCtors->isHidden() || ExportHidden))
     ExportedSymbols.emplace_back(
         WasmExportEntry{WasmSym::CallCtors, WasmSym::CallCtors->getName()});
 
   for (ObjFile *File : Symtab->ObjectFiles) {
     for (Symbol *Sym : File->getSymbols()) {
       if (!Sym->isDefined() || File != Sym->getFile())
         continue;
-      if (Sym->isGlobal())
+      if (isa<GlobalSymbol>(Sym))
         continue;
       if (!Sym->getChunk()->Live)
         continue;
 
       if ((Sym->isHidden() || Sym->isLocal()) && !ExportHidden)
         continue;
       ExportedSymbols.emplace_back(WasmExportEntry{Sym, BudgeLocalName(Sym)});
     }