Misc updates (mostly doc)

tool/input_sdk/lib/core/errors.dart

Index: tool/input_sdk/lib/core/errors.dart
diff --git a/tool/input_sdk/lib/core/errors.dart b/tool/input_sdk/lib/core/errors.dart
index a47838bb0e700a436e9c062a0d1f2f1ee9046426..c11ea2e1a97da25e0c73490a216d7ec025492dc6 100644
--- a/tool/input_sdk/lib/core/errors.dart
+++ b/tool/input_sdk/lib/core/errors.dart
@@ -454,7 +454,7 @@ class NoSuchMethodError extends Error {
    * The [namedArguments] is a map from [Symbol]s to the values of named
    * arguments that the method was called with.
    *
-   * The optional [exisitingArgumentNames] is the expected parameters of a
+   * The optional [existingArgumentNames] is the expected parameters of a
    * method with the same name on the receiver, if available. This is
    * the signature of the method that would have been called if the parameters
    * had matched.