Parser: fix confusion when there are multiple errors to report.

src/parser.cc

Index: src/parser.cc
diff --git a/src/parser.cc b/src/parser.cc
index c6c72fefbba7cdbd9614e467d2942f2ba61dc9e4..de46bb8d1db7c36d12a9e71c26f07b061642ced6 100644
--- a/src/parser.cc
+++ b/src/parser.cc
@@ -452,6 +452,12 @@ bool ParserTraits::IsEvalOrArguments(Handle<String> identifier) const {
 void ParserTraits::ReportMessageAt(Scanner::Location source_location,
                                    const char* message,
                                    Vector<const char*> args) {
+  if (parser_->stack_overflow()) {
+    // Suppress the error message (syntax error or such) in the presence of a
+    // stack overflow. The isolate allows only one pending exception at at time
+    // and we want to report the stack overflow later.
+    return;
+  }
   MessageLocation location(parser_->script_,
                            source_location.beg_pos,
                            source_location.end_pos);
@@ -477,6 +483,12 @@ void ParserTraits::ReportMessage(const char* message,
 void ParserTraits::ReportMessageAt(Scanner::Location source_location,
                                    const char* message,
                                    Vector<Handle<String> > args) {
+  if (parser_->stack_overflow()) {
+    // Suppress the error message (syntax error or such) in the presence of a
+    // stack overflow. The isolate allows only one pending exception at at time
+    // and we want to report the stack overflow later.
+    return;
+  }
   MessageLocation location(parser_->script_,
                            source_location.beg_pos,
                            source_location.end_pos);