[regexp] implement case-insensitive unicode regexps.

src/regexp/arm64/regexp-macro-assembler-arm64.cc

Index: src/regexp/arm64/regexp-macro-assembler-arm64.cc
diff --git a/src/regexp/arm64/regexp-macro-assembler-arm64.cc b/src/regexp/arm64/regexp-macro-assembler-arm64.cc
index 9948597ca0e4b72ee064ab700d838afd05c960f6..b3da580ededd887a791f745157ad666d0bf14617 100644
--- a/src/regexp/arm64/regexp-macro-assembler-arm64.cc
+++ b/src/regexp/arm64/regexp-macro-assembler-arm64.cc
@@ -274,7 +274,7 @@ void RegExpMacroAssemblerARM64::CheckGreedyLoop(Label* on_equal) {
 
 
 void RegExpMacroAssemblerARM64::CheckNotBackReferenceIgnoreCase(
-    int start_reg, bool read_backward, Label* on_no_match) {
+    int start_reg, bool read_backward, bool unicode, Label* on_no_match) {
   Label fallthrough;
 
   Register capture_start_offset = w10;
@@ -388,7 +388,7 @@ void RegExpMacroAssemblerARM64::CheckNotBackReferenceIgnoreCase(
     //   x0: Address byte_offset1 - Address captured substring's start.
     //   x1: Address byte_offset2 - Address of current character position.
     //   w2: size_t byte_length - length of capture in bytes(!)
-    //   x3: Isolate* isolate
+    //   x3: Isolate* isolate or 0 if unicode flag
 
     // Address of start of capture.
     __ Add(x0, input_end(), Operand(capture_start_offset, SXTW));
@@ -400,7 +400,14 @@ void RegExpMacroAssemblerARM64::CheckNotBackReferenceIgnoreCase(
       __ Sub(x1, x1, Operand(capture_length, SXTW));
     }
     // Isolate.
-    __ Mov(x3, ExternalReference::isolate_address(isolate()));
+#ifdef V8_I18N_SUPPORT
+    if (unicode) {
+      __ Mov(x3, Operand(0));
+    } else  // NOLINT
+#endif  // V8_I18N_SUPPORT
+    {
+      __ Mov(x3, ExternalReference::isolate_address(isolate()));
+    }
 
     {
       AllowExternalCallThatCantCauseGC scope(masm_);