Completion for default export should be '.default' (#16742)

* Completion for default export should be '.default'

* Don't include empty string in name table

* getSymbolsInScope() should return local symbols, not exported symbols

* Fix bug: getSymbolAtLocation should work for local symbol too

src/compiler/checker.ts

@@ -11875,6 +11875,8 @@ namespace ts {
         }
 
         function getTypeOfSymbolAtLocation(symbol: Symbol, location: Node) {
+            symbol = symbol.exportSymbol || symbol;
+
             // If we have an identifier or a property access at the given location, if the location is
             // an dotted name expression, and if the location is not an assignment target, obtain the type
             // of the expression (which will reflect control flow analysis). If the expression indeed
@@ -22281,11 +22283,6 @@ namespace ts {
                     }
 
                     switch (location.kind) {
-                        case SyntaxKind.SourceFile:
-                            if (!isExternalOrCommonJsModule(<SourceFile>location)) {
-                                break;
-                            }
-                            // falls through
                         case SyntaxKind.ModuleDeclaration:
                             copySymbols(getSymbolOfNode(location).exports, meaning & SymbolFlags.ModuleMember);
                             break;
@@ -22337,7 +22334,7 @@ namespace ts {
              * @param meaning meaning of symbol to filter by before adding to symbol table
              */
             function copySymbol(symbol: Symbol, meaning: SymbolFlags): void {
-                if (symbol.flags & meaning) {
+                if (getCombinedLocalAndExportSymbolFlags(symbol) & meaning) {
                     const id = symbol.name;
                     // We will copy all symbol regardless of its reserved name because
                     // symbolsToArray will check whether the key is a reserved name and

src/compiler/utilities.ts

@@ -3598,6 +3598,11 @@ namespace ts {
         }
         return previous[previous.length - 1];
     }
+
+    /** See comment on `declareModuleMember` in `binder.ts`. */
+    export function getCombinedLocalAndExportSymbolFlags(symbol: Symbol): SymbolFlags {
+        return symbol.exportSymbol ? symbol.exportSymbol.flags | symbol.flags : symbol.flags;
+    }
 }
 
 namespace ts {