Implement new Function.prototype.toString and fix CreateDynamicFunction parsing

src/parsing/parser.cc

Index: src/parsing/parser.cc
diff --git a/src/parsing/parser.cc b/src/parsing/parser.cc
index 012bc6e00ed3ea3284d2cdce57e99a12af6dea20..bb33a4419d3b3c2c29597ac4babb2ed20d558161 100644
--- a/src/parsing/parser.cc
+++ b/src/parsing/parser.cc
@@ -586,7 +586,8 @@ Parser::Parser(ParseInfo* info)
       cached_parse_data_(nullptr),
       total_preparse_skipped_(0),
       temp_zoned_(false),
-      log_(nullptr) {
+      log_(nullptr),
+      parameters_end_pos_(info->parameters_end_pos()) {
   // Even though we were passed ParseInfo, we should not store it in
   // Parser - this makes sure that Isolate is not accidentally accessed via
   // ParseInfo during background parsing.
@@ -3166,8 +3167,27 @@ ZoneList<Statement*>* Parser::ParseFunction(
 
   if (IsGeneratorFunction(kind)) PrepareGeneratorVariables(&function_state);
 
+  int expected_parameters_end_pos = parameters_end_pos_;
+  if (expected_parameters_end_pos != kNoSourcePosition) {
+    // This is the first function encountered in an only-single-function eval.

[Dan Ehrenberg, 2016/12/06 00:32:13]

I thought this happens only in the Function constructor

[jwolfe, 2017/01/13 00:28:48]

Updated comment to be more clear.

+    parameters_end_pos_ = kNoSourcePosition;
+    // The function name should have been ignored, giving us null here.
+    DCHECK_NULL(function_name);
+  }
+
   ParserFormalParameters formals(function_scope);
   ParseFormalParameterList(&formals, CHECK_OK);
+  if (expected_parameters_end_pos != kNoSourcePosition) {
+    // Check for '(' or ')' shenanigans in the parameter string for dynamic
+    // functions.
+    if (peek_position() != expected_parameters_end_pos) {
+      ReportMessageAt(Scanner::Location(expected_parameters_end_pos,
+                                        expected_parameters_end_pos + 1),
+                      MessageTemplate::kExpectedEndOfParameters);

[Dan Ehrenberg, 2016/12/06 00:32:13]

Will CreateDynamicFunction always trigger eager compilation? If the function
constructor sometimes does lazy compilation, then this logic should be
implemented in the preparser as well. Otherwise, could we add a DCHECK in
Parser::SkipFunction to ensure that parameters_end_pos_ == kNoSourcePosition to
double-check that this never occurs?

[jwolfe, 2017/01/13 00:28:47]

Done. It looks like it's always eagerly parsed. I have a little difficulty
tracing the eager vs lazy logic, but it looked to me like it was going to be
always eager. I added the DCHECK also, and it didn't trigger anywhere in
bot_default+test262 (I made it a CHECK for that test).

+      *ok = false;
+      return nullptr;
+    }
+  }
   Expect(Token::RPAREN, CHECK_OK);
   int formals_end_position = scanner()->location().end_pos;
   *num_parameters = formals.num_parameters();