Remove KernelDriver/IKG.invalidateAll().

pkg/front_end/lib/incremental_kernel_generator.dart

Index: pkg/front_end/lib/incremental_kernel_generator.dart
diff --git a/pkg/front_end/lib/incremental_kernel_generator.dart b/pkg/front_end/lib/incremental_kernel_generator.dart
index 034c0e8ce20f1d97c9affbb32702027ac9573afe..290a23029379c66b6073800e35b7360785af646f 100644
--- a/pkg/front_end/lib/incremental_kernel_generator.dart
+++ b/pkg/front_end/lib/incremental_kernel_generator.dart
@@ -89,15 +89,6 @@ abstract class IncrementalKernelGenerator {
   /// next call to [computeDelta]).
   void invalidate(Uri uri);
 
-  /// Remove all source files from the set of valid sources.  This guarantees
-  /// that all files will be re-read on the next call to [computeDelta].
-  ///
-  /// Note that this does not erase the previous program state; the next time
-  /// [computeDelta] is called, if parts of the program are discovered to be
-  /// unchanged, parts of the previous program state will still be re-used to
-  /// speed up compilation.
-  void invalidateAll();
-
   /// Creates an [IncrementalKernelGenerator] which is prepared to generate
   /// kernel representations of the program whose main library is in the given
   /// [entryPoint].