Move code for instantiating Invocation to Target.

pkg/front_end/lib/src/fasta/compiler_command_line.dart

Index: pkg/front_end/lib/src/fasta/compiler_command_line.dart
diff --git a/pkg/front_end/lib/src/fasta/compiler_command_line.dart b/pkg/front_end/lib/src/fasta/compiler_command_line.dart
index 96e59bb3519e81d4b821c964cd1fb3cc2705a8db..16ed4dbe157698969b582fcb7cde56b026b6cf29 100644
--- a/pkg/front_end/lib/src/fasta/compiler_command_line.dart
+++ b/pkg/front_end/lib/src/fasta/compiler_command_line.dart
@@ -17,6 +17,8 @@ const Map<String, dynamic> optionSpecification = const <String, dynamic>{
   "--packages": Uri,
   "--platform": Uri,
   "-o": Uri,
+  "--target": String,
+  "-t": String,
 };
 
 class CompilerCommandLine extends CommandLine {
@@ -50,6 +52,9 @@ class CompilerCommandLine extends CommandLine {
     if (options.containsKey("-o") && options.containsKey("--output")) {
       return argumentError(usage, "Can't specify both '-o' and '--output'.");
     }
+    if (options.containsKey("-t") && options.containsKey("--target")) {
+      return argumentError(usage, "Can't specify both '-t' and '--target'.");
+    }
     if (programName == "compile_platform" && arguments.length != 3) {
       return argumentError(usage, "Expected three arguments.");
     } else if (arguments.isEmpty) {
@@ -85,6 +90,10 @@ class CompilerCommandLine extends CommandLine {
 
   bool get strongMode => options.containsKey("--strong-mode");
 
+  String get target {
+    return options["-t"] ?? options["--target"] ?? "vm";
+  }
+
   static dynamic withGlobalOptions(String programName, List<String> arguments,
       dynamic f(CompilerContext context)) {
     return CompilerContext.withGlobalOptions(
@@ -165,6 +174,9 @@ Supported options:
     Read the SDK platform from <file>, which should be in Dill/Kernel IR format
     and contain the Dart SDK.
 
+  --target=none|vm|vmcc|vmreify|flutter
+    Specify the target configuration.
+
   --verify
     Check that the generated output is free of various problems. This is mostly
     useful for developers of this compiler or Kernel transformations.