Port #9621 to release-2.0

Author: zhengbli

src/compiler/checker.ts

@@ -3160,6 +3160,9 @@ namespace ts {
                 if (declaration.kind === SyntaxKind.ExportAssignment) {
                     return links.type = checkExpression((<ExportAssignment>declaration).expression);
                 }
+                if (declaration.flags & NodeFlags.JavaScriptFile && declaration.kind === SyntaxKind.JSDocPropertyTag && (<JSDocPropertyTag>declaration).typeExpression) {
+                    return links.type = getTypeFromTypeNode((<JSDocPropertyTag>declaration).typeExpression.type);
+                }
                 // Handle variable, parameter or property
                 if (!pushTypeResolution(symbol, TypeSystemPropertyName.Type)) {
                     return unknownType;

tests/cases/fourslash/server/jsdocTypedefTag.ts

@@ -32,16 +32,24 @@
 //// var numberLike; numberLike./*numberLike*/
 ////
 //// /** @type {Person} */
-//// var p;p./*person*/
+//// var p;p./*person*/;
+//// p.personName./*personName*/;
+//// p.personAge./*personAge*/;
 ////
 //// /** @type {Animal} */
-//// var a;a./*animal*/
+//// var a;a./*animal*/;
+//// a.animalName./*animalName*/;
+//// a.animalAge./*animalAge*/;
 ////
 //// /** @type {Cat} */
-//// var c;c./*cat*/
+//// var c;c./*cat*/;
+//// c.catName./*catName*/;
+//// c.catAge./*catAge*/;
 ////
 //// /** @type {Dog} */
-//// var d;d./*dog*/
+//// var d;d./*dog*/;
+//// d.dogName./*dogName*/;
+//// d.dogAge./*dogAge*/;
 
 goTo.marker('numberLike');
 verify.memberListContains('charAt');
@@ -50,15 +58,31 @@ verify.memberListContains('toExponential');
 goTo.marker('person');
 verify.memberListContains('personName');
 verify.memberListContains('personAge');
+goTo.marker('personName');
+verify.memberListContains('charAt');
+goTo.marker('personAge');
+verify.memberListContains('toExponential');
 
 goTo.marker('animal');
 verify.memberListContains('animalName');
 verify.memberListContains('animalAge');
+goTo.marker('animalName');
+verify.memberListContains('charAt');
+goTo.marker('animalAge');
+verify.memberListContains('toExponential');
 
 goTo.marker('dog');
 verify.memberListContains('dogName');
 verify.memberListContains('dogAge');
+goTo.marker('dogName');
+verify.memberListContains('charAt');
+goTo.marker('dogAge');
+verify.memberListContains('toExponential');
 
 goTo.marker('cat');
 verify.memberListContains('catName');
-verify.memberListContains('catAge');
+verify.memberListContains('catAge');
+goTo.marker('catName');
+verify.memberListContains('charAt');
+goTo.marker('catAge');
+verify.memberListContains('toExponential');