Restore earlier behaviour when parsing non-simple arrow function bodies

Author: caitp

src/compiler/parser.ts

@@ -3040,14 +3040,11 @@ 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);
         }