[benchmark] Fix oversights from the benchmark fork.

The shared libraries for the FfiBoringssl benchmark had been moved up a
level but unfortunately the same change wasn't made for the FfiCall
benchmark.

The IsolateJson benchmark had a typo in the path and broke.

Change-Id: Iec2fec1d5508022d9cfbfb040d80c74b078a0640
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/150024
Reviewed-by: William Hesse <whesse@google.com>

DEPS

@@ -501,7 +501,7 @@ deps = {
       ],
       "dep_type": "cipd",
   },
-  Var("dart_root") + "/benchmarks/FfiCall/dart/native/out/": {
+  Var("dart_root") + "/benchmarks/FfiCall/native/out/": {
       "packages": [
           {
               "package": "dart/benchmarks/fficall",

benchmarks/FfiCall/dart/FfiCall.dart

@@ -20,7 +20,7 @@ import 'dlopen_helper.dart';
 //
 
 DynamicLibrary ffiTestFunctions = dlopenPlatformSpecific("native_functions",
-    path: Platform.script.resolve("native/out/").path);
+    path: Platform.script.resolve("../native/out/").path);
 
 typedef NativeFunction1Uint8 = Uint8 Function(Uint8);
 typedef Function1int = int Function(int);

benchmarks/FfiCall/dart2/FfiCall.dart

@@ -20,7 +20,7 @@ import 'dlopen_helper.dart';
 //
 
 DynamicLibrary ffiTestFunctions = dlopenPlatformSpecific("native_functions",
-    path: Platform.script.resolve("native/out/").path);
+    path: Platform.script.resolve("../native/out/").path);
 
 typedef NativeFunction1Uint8 = Uint8 Function(Uint8);
 typedef Function1int = int Function(int);

benchmarks/IsolateJson/dart2/IsolateJson.dart

@@ -115,7 +115,7 @@ class BenchmarkConfig {
 
 Future<void> main() async {
   final jsonString =
-      File('benchmarks/IsolateJson2/dart/sample.json').readAsStringSync();
+      File('benchmarks/IsolateJson/dart2/sample.json').readAsStringSync();
   final json250KB = utf8.encode(jsonString); // 294356 bytes
   final decoded = json.decode(utf8.decode(json250KB));
   final decoded1MB = <dynamic, dynamic>{