Irregexp: Added derived knowledge of whether we are at the start of input.

src/ast.cc

Index: src/ast.cc
diff --git a/src/ast.cc b/src/ast.cc
index a5f4dc80a18046b0a382566463bc01a24523548c..3197aa90eabcb25b1a1bd90b7f2b99db772096bc 100644
--- a/src/ast.cc
+++ b/src/ast.cc
@@ -250,7 +250,13 @@ bool RegExpAssertion::IsAnchored() {
 
 
 bool RegExpAlternative::IsAnchored() {
-  return this->nodes()->at(0)->IsAnchored();
+  ZoneList<RegExpTree*>* nodes = this->nodes();
+  for (int i = 0; i < nodes->length(); i++) {
+    RegExpTree* node = nodes->at(i);
+    if (node->IsAnchored()) { return true; }
+    if (node->max_match() > 0) { return false; }
+  }
+  return false;
 }