Update Symbol.hashCode

New dart2js version avoids inefficient String.hashCode

[email protected]

Review URL: https://codereview.chromium.org/2040963005 .

Author: rakudrama

pkg/dev_compiler/lib/runtime/dart_sdk.js

@@ -7687,8 +7687,12 @@ dart_library.library('dart_sdk', null, /* Imports */[
       return _internal.Symbol.is(other) && this[_name] == other[_name];
     }
     get hashCode() {
+      let hash = this._hashCode;
+      if (hash != null) return hash;
       let arbitraryPrime = 664597;
-      return 536870911 & arbitraryPrime * dart.notNull(dart.hashCode(this[_name]));
+      hash = 536870911 & arbitraryPrime * dart.notNull(dart.hashCode(this[_name]));
+      this._hashCode = hash;
+      return hash;
     }
     toString() {
       return dart.str`Symbol("${this[_name]}")`;

pkg/dev_compiler/tool/input_sdk/lib/internal/symbol.dart

@@ -112,10 +112,7 @@ class Symbol implements core.Symbol {
 
   bool operator ==(Object other) => other is Symbol && _name == other._name;
 
-  int get hashCode {
-    const arbitraryPrime = 664597;
-    return 0x1fffffff & (arbitraryPrime * _name.hashCode);
-  }
+  external int get hashCode;
 
   toString() => 'Symbol("$_name")';
 

pkg/dev_compiler/tool/input_sdk/patch/internal_patch.dart

@@ -5,12 +5,23 @@
 import 'dart:_js_primitives' show printString;
 import 'dart:_js_helper' show patch;
 import 'dart:_interceptors' show JSArray;
+import 'dart:_foreign_helper' show JS;
 
 @patch
 class Symbol implements core.Symbol {
   @patch
   const Symbol(String name)
       : this._name = name;
+
+  @patch
+  int get hashCode {
+    int hash = JS('int|Null', '#._hashCode', this);
+    if (hash != null) return hash;
+    const arbitraryPrime = 664597;
+    hash = 0x1fffffff & (arbitraryPrime * _name.hashCode);
+    JS('', '#._hashCode = #', this, hash);
+    return hash;
+  }
 }
 
 @patch