[dart2js][js_runtime] Use Array.isArray more consistently

The main reason is to do this change is to avoid inconsistencies in what is considered to be a `JSArray`. Using `Array.isArray` allows js-interop where the JavaScript code subclasses `Array`.

dart2js-production results:

ArrayLoop.pseudopoly.hoisted1-indexing  -50.20%
ArrayLoop.pseudopoly.indexing           -35.18%
Iteration.concat.manual                  11.69%
ListCopy.List.int.unmodifiable.2         12.03%
ListCopy.for.int.2                       12.58%
ListCopy.spread.int.2                    13.57%
ListCopy.toList.fixed.100                16.06%
ListCopy.List.of.fixed.100               16.96%
ListCopy.toList.100                      17.28%
ListCopy.spread.int.cast.2               18.45%
ObjectHash.hash.5                        19.62%
TypedDataPoly.A_UVx5.view.2              21.12%
ObjectHash.manual.5                      21.70%
ListCopy.spread.int.map.2                21.96%
ListCopy.spread.int.cast.100             22.12%
TypedDataPoly.A_UVx5.view.100            23.04%
ListCopy.spread.int.map.100              25.26%
ListCopy.List.of.100                     27.88%
ImagingGaussianBlurOnce                  29.67%
MegaEquality                             37.90%

An investigation of the two regressions shows that they benefit from a micro-benchmarking effect. The previous code was monomorphic at the property access in `receiver.constructor == Array`. If this is forced to be polymorphic, the baseline is quite a bit worse, leading to an improvement in line with some of the other benchmarks.


Change-Id: I5c265b1d7408fbd41da9c6fa17472bf648000c8d
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/287140
Reviewed-by: Nate Biggs <natebiggs@google.com>
Commit-Queue: Stephen Adams <sra@google.com>

pkg/compiler/lib/src/js_emitter/interceptor_stub_generator.dart

@@ -69,7 +69,7 @@ class InterceptorStubGenerator {
           cls == _commonElements.jsMutableArrayClass ||
           cls == _commonElements.jsFixedArrayClass ||
           cls == _commonElements.jsExtendableArrayClass) {
-        condition = js('receiver.constructor == Array');
+        condition = js('Array.isArray(receiver)');
       } else if (cls == _commonElements.jsStringClass) {
         condition = js('(typeof receiver) == "string"');
       } else if (cls == _commonElements.jsNullClass) {
@@ -303,8 +303,7 @@ class InterceptorStubGenerator {
       // For an index operation, this code generates:
       //
       //    if (typeof a0 === "number") {
-      //      if (receiver.constructor == Array ||
-      //          typeof receiver == "string") {
+      //      if (Array.isArray(receiver) || typeof receiver == "string") {
       //        if (a0 >>> 0 === a0 && a0 < receiver.length) {
       //          return receiver[a0];
       //        }
@@ -314,7 +313,7 @@ class InterceptorStubGenerator {
       // For an index set operation, this code generates:
       //
       //    if (typeof a0 === "number") {
-      //      if (receiver.constructor == Array && !receiver.immutable$list) {
+      //      if (Array.isArray(receiver) && !receiver.immutable$list) {
       //        if (a0 >>> 0 === a0 && a0 < receiver.length) {
       //          return receiver[a0] = a1;
       //        }
@@ -343,7 +342,7 @@ class InterceptorStubGenerator {
       if (!containsArray && !containsString) {
         return null;
       }
-      jsAst.Expression arrayCheck = js('receiver.constructor == Array');
+      jsAst.Expression arrayCheck = js('Array.isArray(receiver)');
 
       // Lazy generation of the indexable check. If indexable behavior isn't
       // used, the isJsIndexable function isn't part of the closed world.

sdk/lib/_internal/js_runtime/lib/native_helper.dart

@@ -385,7 +385,7 @@ void initHooks() {
     if (JS('bool', 'typeof # == "function"', transformers)) {
       transformers = [transformers];
     }
-    if (JS('bool', '#.constructor == Array', transformers)) {
+    if (JS('bool', 'Array.isArray(#)', transformers)) {
       for (int i = 0; i < JS('int', '#.length', transformers); i++) {
         var transformer = JS('', '#[#]', transformers, i);
         if (JS('bool', 'typeof # == "function"', transformer)) {