[regexp][cleanup] Using 'using' instead of 'typedef'

Even though both are allowed in the style guide, it recommends to use
'using', as its syntax is more consistent with the rest of C++.
This CL turns all typedefs in src/regexp to 'using' declarations.

R=jgruber@chromium.org

Bug: v8:8834
Change-Id: I2765c3465fec7e8c42c3a84b924522f220ab5676
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1545904Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60585}

src/regexp/interpreter-irregexp.cc

@@ -21,7 +21,7 @@
 namespace v8 {
 namespace internal {
 
-typedef unibrow::Mapping<unibrow::Ecma262Canonicalize> Canonicalize;
+using Canonicalize = unibrow::Mapping<unibrow::Ecma262Canonicalize>;
 
 static bool BackRefMatchesNoCase(Isolate* isolate, int from, int current,
                                  int len, Vector<const uc16> subject,

src/regexp/jsregexp.cc

@@ -1660,14 +1660,9 @@ static bool ShortCutEmitCharacterPair(RegExpMacroAssembler* macro_assembler,
   return false;
 }
 
-
-typedef bool EmitCharacterFunction(Isolate* isolate,
-                                   RegExpCompiler* compiler,
-                                   uc16 c,
-                                   Label* on_failure,
-                                   int cp_offset,
-                                   bool check,
-                                   bool preloaded);
+using EmitCharacterFunction = bool(Isolate* isolate, RegExpCompiler* compiler,
+                                   uc16 c, Label* on_failure, int cp_offset,
+                                   bool check, bool preloaded);
 
 // Only emits letters (things that have case).  Only used for case independent
 // matches.

src/regexp/jsregexp.h

@@ -258,8 +258,8 @@ class DispatchTable : public ZoneObject {
 
   class Config {
    public:
-    typedef uc32 Key;
-    typedef Entry Value;
+    using Key = uc32;
+    using Value = Entry;
     static const uc32 kNoKey;
     static const Entry NoValue() { return Value(); }
     static inline int Compare(uc32 a, uc32 b) {

src/regexp/regexp-ast.h

@@ -303,7 +303,7 @@ class RegExpCharacterClass final : public RegExpTree {
     NEGATED = 1 << 0,
     CONTAINS_SPLIT_SURROGATE = 1 << 1,
   };
-  typedef base::Flags<Flag> CharacterClassFlags;
+  using CharacterClassFlags = base::Flags<Flag>;
 
   RegExpCharacterClass(
       Zone* zone, ZoneList<CharacterRange>* ranges, JSRegExp::Flags flags,