Add missing string length check in regexp engine.

src/x64/regexp-macro-assembler-x64.cc

Index: src/x64/regexp-macro-assembler-x64.cc
diff --git a/src/x64/regexp-macro-assembler-x64.cc b/src/x64/regexp-macro-assembler-x64.cc
index a72a0a0d1d99adcd9ff54c7b3d0a365f15e03ab6..86f7bfe6ca66533853f9c93f03851b05ef7c1e4a 100644
--- a/src/x64/regexp-macro-assembler-x64.cc
+++ b/src/x64/regexp-macro-assembler-x64.cc
@@ -353,6 +353,14 @@ void RegExpMacroAssemblerX64::CheckNotBackReferenceIgnoreCase(
   // In either case succeed immediately.
   __ j(equal, &fallthrough);
 
+  // -----------------------
+  // rdx - Start of capture
+  // rbx - length of capture
+  // Check that there are sufficient characters left in the input.
+  __ movl(rax, rdi);
+  __ addl(rax, rbx);
+  BranchOrBacktrack(greater, on_no_match);
+
   if (mode_ == ASCII) {
     Label loop_increment;
     if (on_no_match == NULL) {