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

src/regexp-macro-assembler-tracer.cc

Index: src/regexp-macro-assembler-tracer.cc
diff --git a/src/regexp-macro-assembler-tracer.cc b/src/regexp-macro-assembler-tracer.cc
index c5c2919c3fb9d5bf71fd1357c99dacc19cd70c1a..522042262f58e561c88f9f00464b7ad5685b9078 100644
--- a/src/regexp-macro-assembler-tracer.cc
+++ b/src/regexp-macro-assembler-tracer.cc
@@ -37,8 +37,8 @@ RegExpMacroAssemblerTracer::RegExpMacroAssemblerTracer(
     RegExpMacroAssembler* assembler) :
   assembler_(assembler) {
   unsigned int type = assembler->Implementation();
-  ASSERT(type < 3);
-  const char* impl_names[3] = {"IA32", "ARM", "Bytecode"};
+  ASSERT(type < 4);
+  const char* impl_names[3] = {"IA32", "ARM", "X64", "Bytecode"};
   PrintF("RegExpMacroAssembler%s();\n", impl_names[type]);
 }