Validate that all instructions dominate their inputs. And fix a bug where that did not happen.

lib/compiler/implementation/ssa/codegen.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.
 
 class SsaCodeGeneratorTask extends CompilerTask {
   final JavaScriptBackend backend;
   SsaCodeGeneratorTask(JavaScriptBackend backend)
       : this.backend = backend,
         super(backend.compiler);
   String get name() => 'SSA code generator';
@@ skipping 708 matching lines @@
     addIndented("try {\n");
     indent++;
     generateStatements(info.body);
     indent--;
     addIndented("}");
     if (info.catchBlock !== null) {
       // Printing the catch part.
       HParameterValue exception = info.catchVariable;
       String name = temporary(exception);
       parameterNames[exception.element] = name;
-      buffer.add('catch ($name) {\n');
+      buffer.add(' catch ($name) {\n');
       indent++;
       generateStatements(info.catchBlock);
       parameterNames.remove(exception.element);
       indent--;
       addIndented('}');
     }
     if (info.finallyBlock != null) {
       buffer.add(" finally {\n");
       indent++;
       generateStatements(info.finallyBlock);
@@ skipping 1892 matching lines @@
       startBailoutSwitch();
     }
   }
 
   void endLabeledBlock(HLabeledBlockInformation labeledBlockInfo) {
     if (labeledBlockInfo.body.start.hasGuards()) {
       endBailoutSwitch();
     }
   }
 }