First stab at "pub run" command.

sdk/lib/_internal/pub/test/version_solver_test.dart

Index: sdk/lib/_internal/pub/test/version_solver_test.dart
diff --git a/sdk/lib/_internal/pub/test/version_solver_test.dart b/sdk/lib/_internal/pub/test/version_solver_test.dart
index 54c89213f2da40c709f66fbd6e95ac12d2c242c0..b5302cb7e498c7d0b9642f53c65b9274ee5450e8 100644
--- a/sdk/lib/_internal/pub/test/version_solver_test.dart
+++ b/sdk/lib/_internal/pub/test/version_solver_test.dart
@@ -27,7 +27,7 @@ main() {
   initConfig();
 
   // Uncomment this to debug failing tests.
-  // log.showSolver();
+  // log.verbosity = log.Verbosity.SOLVER;
 
   // Since this test isn't run from the SDK, it can't find the "version" file
   // to load. Instead, just manually inject a version.
@@ -1067,7 +1067,7 @@ testResolve(String description, Map packages, {
 solo_testResolve(String description, Map packages, {
     Map lockfile, Map overrides, Map result, FailMatcherBuilder error,
     int maxTries}) {
-  log.showSolver();
+  log.verbosity = log.Verbosity.SOLVER;
   _testResolve(solo_test, description, packages, lockfile: lockfile,
       overrides: overrides, result: result, error: error, maxTries: maxTries);
 }