Revert "Revert "Upgrade to 5.0.71.48"" DO NOT MERGE

This reverts commit f2e3994fa5148cc3d9946666f0b0596290192b0e,
and updates the x64 makefile properly so it doesn't break that
build.

FPIIM-449

Change-Id: Ib83e35bfbae6af627451c926a9650ec57c045605
(cherry picked from commit 109988c7ccb6f3fd1a58574fa3dfb88beaef6632)
diff --git a/src/regexp/arm64/regexp-macro-assembler-arm64.cc b/src/regexp/arm64/regexp-macro-assembler-arm64.cc
index 9948597..941ccea 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::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 @@
     //   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 @@
       __ 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_);
@@ -991,9 +998,12 @@
         // Offset from the end is zero if we already reached the end.
         __ Cbz(current_input_offset(), &return_w0);
         // Advance current position after a zero-length match.
+        Label advance;
+        __ bind(&advance);
         __ Add(current_input_offset(),
                current_input_offset(),
                Operand((mode_ == UC16) ? 2 : 1));
+        if (global_unicode()) CheckNotInSurrogatePair(0, &advance);
       }
 
       __ B(&load_char_start_regexp);