Mojo JS Bindings: add support for associative arrays (Mojo map type)

mojo/public/interfaces/bindings/tests/test_structs.mojom

Index: mojo/public/interfaces/bindings/tests/test_structs.mojom
diff --git a/mojo/public/interfaces/bindings/tests/test_structs.mojom b/mojo/public/interfaces/bindings/tests/test_structs.mojom
index 6af00866fec053dbc001cc1572a839ca01d6e611..7674611778b738a67a81588d2cf3f26b57b0afd0 100644
--- a/mojo/public/interfaces/bindings/tests/test_structs.mojom
+++ b/mojo/public/interfaces/bindings/tests/test_structs.mojom
@@ -108,4 +108,31 @@ struct ScopedConstants {
   int32 f6 = ALSO_TEN;
 };
 
-}
+// Used to verify that all possible Map key field types can be encoded and
+// decoded successfully.
+
+struct MapKeyTypes {
+  map<bool, bool> f0;
+  map<int8, int8> f1;
+  map<uint8, uint8> f2;
+  map<int16, int16> f3;
+  map<uint16, uint16> f4;
+  map<int32, int32> f5;
+  map<uint32, uint32> f6;
+  map<int64, int64> f7;
+  map<uint64, uint64> f8;
+  map<float, float> f9;
+  map<double, double> f10;
+  map<string, string> f11;
+};
+
+// Used to verify that some common value types can be encoded and decoded
+// successfully.
+
+struct MapValueTypes {
+  map<string, array<string>> f0;
+  map<string, array<string>?> f1;
+  map<string, array<string?>> f2;
+};
+
+}