Restore earlier behaviour when parsing non-simple arrow function bodies

Author: caitp

src/compiler/parser.ts

@@ -3046,14 +3046,11 @@ module ts {
 
  // If we have an arrow, then try to parse the body. Even if not, try to parse if we
  // have an opening brace, just in case we're in an error state.
- arrowFunction.equalsGreaterThanToken = parseExpectedToken(SyntaxKind.EqualsGreaterThanToken, false, Diagnostics._0_expected, "=>");
- if (arrowFunction.equalsGreaterThanToken.kind === SyntaxKind.EqualsGreaterThanToken || token === SyntaxKind.OpenBraceToken) {
- arrowFunction.body = parseArrowFunctionExpressionBody();
- }
- else {
- // If not, we're probably better off bailing out and returning a bogus function expression.
- arrowFunction.body = parseIdentifier();
- }
+ var lastToken = token;
+ arrowFunction.equalsGreaterThanToken = parseExpectedToken(SyntaxKind.EqualsGreaterThanToken, /*reportAtCurrentPosition:*/false, Diagnostics._0_expected, "=>");
+ arrowFunction.body = (lastToken === SyntaxKind.EqualsGreaterThanToken || lastToken === SyntaxKind.OpenBraceToken)
+ ? parseArrowFunctionExpressionBody()
+ : parseIdentifier();
 
  return finishNode(arrowFunction);
  }