Fix bug in word-boundary-lookahead followed by end-of-input assertion.

src/jsregexp.cc

Index: src/jsregexp.cc
diff --git a/src/jsregexp.cc b/src/jsregexp.cc
index 0ae8bd34df23641bebf25bf497423e309c6d0119..9a1f1f114c0145de49657882f6df3868d5a8db78 100644
--- a/src/jsregexp.cc
+++ b/src/jsregexp.cc
@@ -4872,17 +4872,18 @@ void Analysis::VisitAssertion(AssertionNode* that) {
 
     SetRelation word_relation =
         CharacterRange::WordCharacterRelation(following_chars);
-    if (word_relation.ContainedIn()) {
-      // Following character is definitely a word character.
+    if (word_relation.Disjoint()) {
+      // Includes the case where following_chars is empty (e.g., end-of-input).
+      // Following character is definitely *not* a word character.
       type = (type == AssertionNode::AT_BOUNDARY) ?
-                  AssertionNode::AFTER_NONWORD_CHARACTER :
-                  AssertionNode::AFTER_WORD_CHARACTER;
+                 AssertionNode::AFTER_WORD_CHARACTER :
+                 AssertionNode::AFTER_NONWORD_CHARACTER;
       that->set_type(type);
-    } else if (word_relation.Disjoint()) {
-      // Following character is definitely *not* a word character.
+    } else if (word_relation.ContainedIn()) {
+      // Following character is definitely a word character.
       type = (type == AssertionNode::AT_BOUNDARY) ?
-                  AssertionNode::AFTER_WORD_CHARACTER :
-                  AssertionNode::AFTER_NONWORD_CHARACTER;
+                 AssertionNode::AFTER_NONWORD_CHARACTER :
+                 AssertionNode::AFTER_WORD_CHARACTER;
       that->set_type(type);
     }
   }