Dynamically load packages for dartdevc tests in test.dart.

pkg/dev_compiler/lib/src/compiler/compiler.dart

Index: pkg/dev_compiler/lib/src/compiler/compiler.dart
diff --git a/pkg/dev_compiler/lib/src/compiler/compiler.dart b/pkg/dev_compiler/lib/src/compiler/compiler.dart
index ac1d60a6e66eee332fbae639b6ecacefb57459bf..73f0914dfbf6e45c41c33d63f2808289e910428f 100644
--- a/pkg/dev_compiler/lib/src/compiler/compiler.dart
+++ b/pkg/dev_compiler/lib/src/compiler/compiler.dart
@@ -254,7 +254,7 @@ class CompilerOptions {
   /// The file extension for summaries.
   final String summaryExtension;
 
-  /// Whether to preserve metdata only accessible via mirrors
+  /// Whether to preserve metdata only accessible via mirrors.
   final bool emitMetadata;
 
   /// Whether to force compilation of code with static errors.
@@ -267,16 +267,16 @@ class CompilerOptions {
   /// Whether to emit Closure Compiler-friendly code.
   final bool closure;
 
-  /// Hoist the types at instance creation sites
+  /// Hoist the types at instance creation sites.
   final bool hoistInstanceCreation;
 
-  /// Hoist types from class signatures
+  /// Hoist types from class signatures.
   final bool hoistSignatureTypes;
 
-  /// Name types in type tests
+  /// Name types in type tests.
   final bool nameTypeTests;
 
-  /// Hoist types in type tests
+  /// Hoist types in type tests.
   final bool hoistTypeTests;
 
   /// Enable ES6 destructuring of named parameters. Off by default.