Fix 56 hints in pkg/compiler

pkg/compiler/lib/src/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;
 
 class SsaFunctionCompiler implements FunctionCompiler {
   SsaCodeGeneratorTask generator;
   SsaBuilderTask builder;
   SsaOptimizerTask optimizer;
@@ skipping 7536 matching lines @@
 
     if (isExpression) {
       assert(thenValue != null && elseValue != null);
       JavaScriptBackend backend = builder.backend;
       HPhi phi = new HPhi.manyInputs(
           null, <HInstruction>[thenValue, elseValue], backend.dynamicType);
       joinBranch.block.addPhi(phi);
       builder.stack.add(phi);
     }
 
-    HBasicBlock thenBlock = thenBranch.block;
-    HBasicBlock elseBlock = elseBranch.block;
     HBasicBlock joinBlock;
     // If at least one branch did not abort, open the joinBranch.
     if (!joinBranch.block.predecessors.isEmpty) {
       startBranch(joinBranch);
       joinBlock = joinBranch.block;
     }
 
     HIfBlockInformation info =
         new HIfBlockInformation(
           new HSubExpressionBlockInformation(conditionBranch.graph),
@@ skipping 95 matching lines @@
     if (unaliased is TypedefType) throw 'unable to unalias $type';
     unaliased.accept(this, builder);
   }
 
   void visitDynamicType(DynamicType type, SsaBuilder builder) {
     JavaScriptBackend backend = builder.compiler.backend;
     ClassElement cls = backend.findHelper('DynamicRuntimeType');
     builder.push(new HDynamicType(type, new TypeMask.exact(cls, classWorld)));
   }
 }