Support conditional directives in the options file.

pkg/analyzer/lib/src/generated/incremental_resolver.dart

Index: pkg/analyzer/lib/src/generated/incremental_resolver.dart
diff --git a/pkg/analyzer/lib/src/generated/incremental_resolver.dart b/pkg/analyzer/lib/src/generated/incremental_resolver.dart
index 7cc84d30453dd3d725a59b5ebb838a32cf6efb35..fc8c86022a9bbf20183d4af44943a73f0bb9df01 100644
--- a/pkg/analyzer/lib/src/generated/incremental_resolver.dart
+++ b/pkg/analyzer/lib/src/generated/incremental_resolver.dart
@@ -1621,6 +1621,7 @@ class PoorMansIncrementalResolver {
       RecordingErrorListener errorListener = new RecordingErrorListener();
       Parser parser = new Parser(_unitSource, errorListener);
       AnalysisOptions options = _unitElement.context.analysisOptions;
+      parser.parseConditionalDirectives = options.enableConditionalDirectives;
       parser.parseGenericMethods = options.enableGenericMethods;
       CompilationUnit unit = parser.parseCompilationUnit(token);
       _newParseErrors = errorListener.errors;