Instead of writing text from source file use text property to write text of synthesized node

Fixes #4364

tests/cases/compiler/decoratorMetadataWithConstructorType.ts

@@ -0,0 +1,21 @@
+// @noemithelpers: true
+// @experimentaldecorators: true
+// @emitdecoratormetadata: true
+// @target: es5
+// @module: commonjs
+
+declare var console: {
+    log(msg: string): void;
+};
+
+class A {
+    constructor() { console.log('new A'); }
+}
+
+function decorator(target: Object, propertyKey: string) {
+}
+
+export class B {
+    @decorator
+    x: A = new A();
+}