Remove deprecated Expect from the libraries.

tests/standalone/debugger/debug_lib.dart

Index: tests/standalone/debugger/debug_lib.dart
diff --git a/tests/standalone/debugger/debug_lib.dart b/tests/standalone/debugger/debug_lib.dart
index 26f372508ee2d5b9a101cadc5a41b3f99ab6d6cd..ea169dcf33a3d61df7101e3be9cad320ef20aacb 100644
--- a/tests/standalone/debugger/debug_lib.dart
+++ b/tests/standalone/debugger/debug_lib.dart
@@ -455,7 +455,7 @@ class Debugger {
       targetProcess.kill();
       print("Target process killed");
     }
-    Expect.isTrue(!errorsDetected);
+    if (errorsDetected) throw "Errors detected";
     exit(errors.length);
   }
 }
@@ -487,7 +487,7 @@ bool RunScript(List script) {
         print("Debug target process started");
         process.stdin.close();
         process.exitCode.then((int exitCode) {
-          Expect.equals(0, exitCode);
+          if (exitCode != 0) throw "bad exit code: $exitCode";
           print("Debug target process exited with exit code $exitCode");
         });
         var debugger =