Thread the current isolate through a few places, avoiding Isolate::Current().

src/jsregexp.h

Index: src/jsregexp.h
diff --git a/src/jsregexp.h b/src/jsregexp.h
index 42c76fbd67666a8415a5a1091fffa4bc6e118460..8875de9eb2316cb27511cd7b9a9408bc08fd4f41 100644
--- a/src/jsregexp.h
+++ b/src/jsregexp.h
@@ -1466,12 +1466,12 @@ class RegExpEngine: public AllStatic {
 
 class OffsetsVector {
  public:
-  explicit inline OffsetsVector(int num_registers)
+  inline OffsetsVector(int num_registers, Isolate* isolate)
       : offsets_vector_length_(num_registers) {
     if (offsets_vector_length_ > Isolate::kJSRegexpStaticOffsetsVectorSize) {
       vector_ = NewArray<int>(offsets_vector_length_);
     } else {
-      vector_ = Isolate::Current()->jsregexp_static_offsets_vector();
+      vector_ = isolate->jsregexp_static_offsets_vector();
     }
   }
   inline ~OffsetsVector() {