Add flag to AnalysisOptions to be able to disable deferred loading.

editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/parser/Parser.java

Index: editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/parser/Parser.java
diff --git a/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/parser/Parser.java b/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/parser/Parser.java
index 150368cf910a219407848063fedb29e268ba5ea9..85ca3568271f8069a2cc3e8cd5a43712c1b50d30 100644
--- a/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/parser/Parser.java
+++ b/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/parser/Parser.java
@@ -19,6 +19,7 @@ import com.google.dart.engine.ast.*;
 import com.google.dart.engine.error.AnalysisError;
 import com.google.dart.engine.error.AnalysisErrorListener;
 import com.google.dart.engine.error.BooleanErrorListener;
+import com.google.dart.engine.internal.context.AnalysisOptionsImpl;
 import com.google.dart.engine.internal.parser.CommentAndMetadata;
 import com.google.dart.engine.internal.parser.FinalConstVarOrType;
 import com.google.dart.engine.internal.parser.Modifiers;
@@ -94,6 +95,11 @@ public class Parser {
   private boolean parseFunctionBodies = true;
 
   /**
+   * A flag indicating whether parser is to parse deferred libraries.
+   */
+  private boolean parseDeferredLibraries = AnalysisOptionsImpl.DEFAULT_ENABLE_DEFERRED_LOADING;
+
+  /**
    * The next token to be parsed.
    */
   private Token currentToken;
@@ -218,6 +224,15 @@ public class Parser {
   }
 
   /**
+   * Set whether parser is to parse deferred libraries.
+   * 
+   * @param parseDeferredLibraries {@code true} if parser is to parse deferred libraries
+   */
+  public void setParseDeferredLibraries(boolean parseDeferredLibraries) {
+    this.parseDeferredLibraries = parseDeferredLibraries;
+  }
+
+  /**
    * Set whether parser is to parse function bodies.
    * 
    * @param parseFunctionBodies {@code true} if parser is to parse function bodies
@@ -4201,7 +4216,12 @@ public class Parser {
     Token asToken = null;
     SimpleIdentifier prefix = null;
     if (matchesKeyword(Keyword.DEFERRED)) {
-      deferredToken = getAndAdvance();
+      if (parseDeferredLibraries) {
+        deferredToken = getAndAdvance();
+      } else {
+        reportErrorForCurrentToken(ParserErrorCode.DEFERRED_IMPORTS_NOT_SUPPORTED);
+        advance();
+      }
     }
     if (matchesKeyword(Keyword.AS)) {
       asToken = getAndAdvance();