Merge pull request microsoft#3719 from Microsoft/createNodePos

Change default node pos/end to -1

Author: rbuckton

src/compiler/core.ts

@@ -764,8 +764,8 @@ namespace ts {
             }
             Node.prototype = {
                 kind: kind,
-                pos: 0,
-                end: 0,
+                pos: -1,
+                end: -1,
                 flags: 0,
                 parent: undefined,
             };

src/compiler/utilities.ts

@@ -144,7 +144,7 @@ namespace ts {
             return true;
         }
 
-        return node.pos === node.end && node.kind !== SyntaxKind.EndOfFileToken;
+        return node.pos === node.end && node.pos >= 0 && node.kind !== SyntaxKind.EndOfFileToken;
     }
 
     export function nodeIsPresent(node: Node) {
@@ -1428,8 +1428,6 @@ namespace ts {
 
     export function createSynthesizedNode(kind: SyntaxKind, startsOnNewLine?: boolean): Node {
         let node = <SynthesizedNode>createNode(kind);
-        node.pos = -1;
-        node.end = -1;
         node.startsOnNewLine = startsOnNewLine;
         return node;
     }

src/services/services.ts

@@ -7387,8 +7387,8 @@ namespace ts {
                 }
                 let proto = kind === SyntaxKind.SourceFile ? new SourceFileObject() : new NodeObject();
                 proto.kind = kind;
-                proto.pos = 0;
-                proto.end = 0;
+                proto.pos = -1;
+                proto.end = -1;
                 proto.flags = 0;
                 proto.parent = undefined;
                 Node.prototype = proto;