use proper notation for true, false, and null in doc comments

sdk/lib/_internal/compiler/implementation/ssa/builder.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of ssa;
 
 /**
  * A special element for the extra parameter taken by intercepted
  * methods. We need to override [Element.computeType] because our
  * optimizers may look at its declared type.
@@ skipping 299 matching lines @@
       // constructor call the constructor with `null`.
       HParameterValue value =
           new HParameterValue(parameter, new TypeMask.exact(cls));
       builder.graph.explicitReceiverParameter = value;
       builder.graph.entry.addAtEntry(value);
     }
   }
 
   /**
    * Returns true if the local can be accessed directly. Boxed variables or
-   * captured variables that are stored in the closure-field return [false].
+   * captured variables that are stored in the closure-field return [:false:].
    */
   bool isAccessedDirectly(Element element) {
     assert(element != null);
     return redirectionMapping[element] == null
         && !closureData.usedVariablesInTry.contains(element);
   }
 
   bool isStoredInClosureField(Element element) {
     assert(element != null);
     if (isAccessedDirectly(element)) return false;
@@ skipping 6074 matching lines @@
     DartType unaliased = type.unalias(builder.compiler);
     if (unaliased is TypedefType) throw 'unable to unalias $type';
     unaliased.accept(this, builder);
   }
 
   void visitDynamicType(DynamicType type, SsaFromAstMixin builder) {
     ClassElement cls = builder.compiler.findHelper('DynamicRuntimeType');
     builder.push(new HDynamicType(type, new TypeMask.exact(cls)));
   }
 }