Revert "Change SDK/DartEditor versioning scheme to semantic versions."

dart/sdk/lib/_internal/pub/lib/src/solver/backtracking_solver.dart

Index: dart/sdk/lib/_internal/pub/lib/src/solver/backtracking_solver.dart
diff --git a/dart/sdk/lib/_internal/pub/lib/src/solver/backtracking_solver.dart b/dart/sdk/lib/_internal/pub/lib/src/solver/backtracking_solver.dart
index cefa4da4012964593cf1361e506f1859caace32c..c38295c348871f726025f2b38cd63fb1115e7704 100644
--- a/dart/sdk/lib/_internal/pub/lib/src/solver/backtracking_solver.dart
+++ b/dart/sdk/lib/_internal/pub/lib/src/solver/backtracking_solver.dart
@@ -630,6 +630,12 @@ class Traverser {
 /// Ensures that if [pubspec] has an SDK constraint, then it is compatible
 /// with the current SDK. Throws a [SolveFailure] if not.
 void _validateSdkConstraint(Pubspec pubspec) {
+  // If the user is running a continouous build of the SDK, just disable SDK
+  // constraint checking entirely. The actual version number you get is
+  // impossibly old and not correct. We'll just assume users on continuous
+  // know what they're doing.
+  if (sdk.isBleedingEdge) return;
+
   if (pubspec.environment.sdkVersion.allows(sdk.version)) return;
 
   throw new BadSdkVersionException(pubspec.name,