Use a "jsonrpc" field rather than "json-rpc" in the VM service.

runtime/vm/service_test.cc

Index: runtime/vm/service_test.cc
diff --git a/runtime/vm/service_test.cc b/runtime/vm/service_test.cc
index 8c16909accce1a7f91d1de2717027601f2a1dbbc..bbcd2a4f56af111198c91342982eb23e6456595b 100644
--- a/runtime/vm/service_test.cc
+++ b/runtime/vm/service_test.cc
@@ -533,12 +533,12 @@ TEST_CASE(Service_EmbedderRootHandler) {
   service_msg = Eval(lib, "[0, port, '0', 'alpha', [], []]");
   Service::HandleRootMessage(service_msg);
   handler.HandleNextMessage();
-  EXPECT_STREQ("{\"json-rpc\":\"2.0\", \"result\":alpha, \"id\":\"0\"}",
+  EXPECT_STREQ("{\"jsonrpc\":\"2.0\", \"result\":alpha, \"id\":\"0\"}",
                handler.msg());
   service_msg = Eval(lib, "[0, port, '0', 'beta', [], []]");
   Service::HandleRootMessage(service_msg);
   handler.HandleNextMessage();
-  EXPECT_STREQ("{\"json-rpc\":\"2.0\", \"result\":beta, \"id\":\"0\"}",
+  EXPECT_STREQ("{\"jsonrpc\":\"2.0\", \"result\":beta, \"id\":\"0\"}",
                handler.msg());
 }
 
@@ -573,12 +573,12 @@ TEST_CASE(Service_EmbedderIsolateHandler) {
   service_msg = Eval(lib, "[0, port, '0', 'alpha', [], []]");
   Service::HandleIsolateMessage(isolate, service_msg);
   handler.HandleNextMessage();
-  EXPECT_STREQ("{\"json-rpc\":\"2.0\", \"result\":alpha, \"id\":\"0\"}",
+  EXPECT_STREQ("{\"jsonrpc\":\"2.0\", \"result\":alpha, \"id\":\"0\"}",
                handler.msg());
   service_msg = Eval(lib, "[0, port, '0', 'beta', [], []]");
   Service::HandleIsolateMessage(isolate, service_msg);
   handler.HandleNextMessage();
-  EXPECT_STREQ("{\"json-rpc\":\"2.0\", \"result\":beta, \"id\":\"0\"}",
+  EXPECT_STREQ("{\"jsonrpc\":\"2.0\", \"result\":beta, \"id\":\"0\"}",
                handler.msg());
 }