Option to disable syntax highlighter and use mostly semantic highlighter. Tests.

editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/ui/DartUiDebug.java

Index: editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/ui/DartUiDebug.java
diff --git a/editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/ui/DartUiDebug.java b/editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/ui/DartUiDebug.java
new file mode 100644
index 0000000000000000000000000000000000000000..fe01c99b64ff61f3316bdf962e849da92069d8b2
--- /dev/null
+++ b/editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/ui/DartUiDebug.java
@@ -0,0 +1,41 @@
+/*
+ * Copyright (c) 2012, the Dart project authors.
+ * 
+ * Licensed under the Eclipse Public License v1.0 (the "License"); you may not use this file except
+ * in compliance with the License. You may obtain a copy of the License at
+ * 
+ * http://www.eclipse.org/legal/epl-v10.html
+ * 
+ * Unless required by applicable law or agreed to in writing, software distributed under the License
+ * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+ * or implied. See the License for the specific language governing permissions and limitations under
+ * the License.
+ */
+package com.google.dart.tools.ui;
+
+import com.google.dart.compiler.util.apache.StringUtils;
+
+import org.eclipse.core.runtime.Platform;
+
+/**
+ * Debug/Tracing options for the {@link DartUI} plugin.
+ */
+public class DartUiDebug {
+  public static final boolean USE_ONLY_SEMANTIC_HIGHLIGHTER = isOptionTrue("experimental/useOnlySemanticHighlighter");
+
+  /**
+   * @return <code>true</code> if option has value "true".
+   */
+  private static boolean isOptionTrue(String optionSuffix) {
+    return isOptionValue(optionSuffix, "true");
+  }
+
+  /**
+   * @return <code>true</code> if option has "expected" value.
+   */
+  private static boolean isOptionValue(String optionSuffix, String expected) {
+    String value = Platform.getDebugOption(DartUI.ID_PLUGIN + "/" + optionSuffix);
+    return StringUtils.equalsIgnoreCase(value, expected);
+  }
+
+}