Set correct methods name

packages/babel-helpers/src/helpers.js

@@ -1236,6 +1236,8 @@ helpers.decorate = helper("7.1.5")`
   function _createElementDescriptor(
     def /*: ElementDefinition */,
   ) /*: ElementDescriptor */ {
+    var key = toPropertyKey(def.key);
+
     var descriptor /*: PropertyDescriptor */;
     if (def.kind === "method") {
       descriptor = {
@@ -1244,6 +1246,10 @@ helpers.decorate = helper("7.1.5")`
         configurable: true,
         enumerable: false,
       };
+      Object.defineProperty(def.value, "name", {
+        value: typeof key === "symbol" ? "" : key,
+        configurable: true,
+      });
     } else if (def.kind === "get") {
       descriptor = { get: def.value, configurable: true, enumerable: false };
     } else if (def.kind === "set") {
@@ -1254,7 +1260,7 @@ helpers.decorate = helper("7.1.5")`
 
     var element /*: ElementDescriptor */ = {
       kind: def.kind === "field" ? "field" : "method",
-      key: def.key,
+      key: key,
       placement: def.static
         ? "static"
         : def.kind === "field"

packages/babel-plugin-proposal-decorators/test/fixtures/misc/method-name/exec.js

@@ -0,0 +1,8 @@
+function decorator() {}
+
+@decorator
+class Foo {
+  method() {}
+}
+
+expect(Foo.prototype.method.name).toBe("method");

packages/babel-plugin-proposal-decorators/test/fixtures/misc/options.json

@@ -0,0 +1,12 @@
+{
+  "plugins": [
+    ["proposal-decorators", { "decoratorsBeforeExport": false }],
+    "proposal-class-properties",
+    [
+      "external-helpers",
+      {
+        "helperVersion": "7.1.5"
+      }
+    ]
+  ]
+}

packages/babel-plugin-proposal-decorators/test/fixtures/misc/to-primitive/exec.js

@@ -0,0 +1,16 @@
+let calls = 0;
+const baz = {
+  [Symbol.toPrimitive]() {
+    calls++;
+    return "baz";
+  }
+}
+
+function dec() {}
+
+@dec
+class A {
+  [baz]() {}
+}
+
+expect(calls).toBe(1);