Implement object literal parsing; Instantiate classes from object literals

Essentially, if the contextual type is a class with a constructor that takes zero arguments or doesn't have a constructor at all, an object literal can be used to initialize a new instance of that class with preset values.

src/ast.ts

@@ -432,6 +432,18 @@ export abstract class Node {
     return expr;
   }
 
+  static createObjectLiteralExpression(
+    names: IdentifierExpression[],
+    values: Expression[],
+    range: Range
+  ): ObjectLiteralExpression {
+    var expr = new ObjectLiteralExpression();
+    expr.range = range;
+    expr.names = names;
+    expr.values = values;
+    return expr;
+  }
+
   static createParenthesizedExpression(
     expression: Expression,
     range: Range
@@ -1363,6 +1375,16 @@ export class NullExpression extends IdentifierExpression {
   text = "null";
 }
 
+/** Represents an object literal expression. */
+export class ObjectLiteralExpression extends LiteralExpression {
+  literalKind = LiteralKind.OBJECT;
+
+  /** Field names. */
+  names: IdentifierExpression[];
+  /** Field values. */
+  values: Expression[];
+}
+
 /** Represents a parenthesized expression. */
 export class ParenthesizedExpression extends Expression {
   kind = NodeKind.PARENTHESIZED;