Remove implicit uint8_t to char cast in string replace.

src/runtime/runtime-regexp.cc

Index: src/runtime/runtime-regexp.cc
diff --git a/src/runtime/runtime-regexp.cc b/src/runtime/runtime-regexp.cc
index e2cf2028d9da87fc66af6efb856e83fc865fef85..64a2d57cf5edabad5b02d953c6ccd5367e98647d 100644
--- a/src/runtime/runtime-regexp.cc
+++ b/src/runtime/runtime-regexp.cc
@@ -278,7 +278,7 @@ void CompiledReplacement::Apply(ReplacementStringBuilder* builder,
 }
 
 
-void FindOneByteStringIndices(Vector<const uint8_t> subject, char pattern,
+void FindOneByteStringIndices(Vector<const uint8_t> subject, uint8_t pattern,
                               ZoneList<int>* indices, unsigned int limit,
                               Zone* zone) {
   DCHECK(limit > 0);