Restrict analyzer/front_end/kernel SDK versions to dev.48+.

Change-Id: If341e8aa3503881bb44e445c39e5f821fd213bfd
Reviewed-on: https://dart-review.googlesource.com/55000
Reviewed-by: Kevin Moore <kevmoo@google.com>
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Commit-Queue: Janice Collins <jcollins@google.com>
diff --git a/pkg/analyzer/pubspec.yaml b/pkg/analyzer/pubspec.yaml
index e1ac2c9..03cdb82 100644
--- a/pkg/analyzer/pubspec.yaml
+++ b/pkg/analyzer/pubspec.yaml
@@ -4,7 +4,7 @@
 description: Static analyzer for Dart.
 homepage: https://github.com/dart-lang/sdk/tree/master/pkg/analyzer
 environment:
-  sdk: '>=2.0.0-dev <2.0.0'
+  sdk: '>=2.0.0-dev.48.0 <2.0.0'
 dependencies:
   args: '>=0.12.1 <2.0.0'
   charcode: ^1.1.0
diff --git a/pkg/front_end/pubspec.yaml b/pkg/front_end/pubspec.yaml
index ef12045..90c0247 100644
--- a/pkg/front_end/pubspec.yaml
+++ b/pkg/front_end/pubspec.yaml
@@ -6,7 +6,7 @@
 description: Front end for compilation of Dart code.
 homepage: https://github.com/dart-lang/sdk/tree/master/pkg/front_end
 environment:
-  sdk: '>=1.12.0 <2.0.0'
+  sdk: '>=2.0.0-dev.48.0 <2.0.0'
 dependencies:
   charcode: '^1.1.1'
   convert: '^2.0.1'
diff --git a/pkg/kernel/pubspec.yaml b/pkg/kernel/pubspec.yaml
index f827fc8..d84856f 100644
--- a/pkg/kernel/pubspec.yaml
+++ b/pkg/kernel/pubspec.yaml
@@ -6,7 +6,7 @@
 description: Dart IR (Intermediate Representation)
 homepage: https://github.com/dart-lang/sdk/tree/master/pkg/kernel
 environment:
-  sdk: ">=1.8.0 <2.0.0"
+  sdk: '>=2.0.0-dev.48.0 <2.0.0'
 dependencies:
   path: ^1.3.9
   args: '>=0.13.4 <2.0.0'