Revert "dart2js: Redo known-type analysis after load-elimination"

pkg/compiler/lib/src/ssa/optimize.dart

Index: pkg/compiler/lib/src/ssa/optimize.dart
diff --git a/pkg/compiler/lib/src/ssa/optimize.dart b/pkg/compiler/lib/src/ssa/optimize.dart
index 9d8e316ec937ed6e13a8dbff23019cb446b40a10..b7b0c0ac5b2bc9e668d10487bfbfc1021d9043d6 100644
--- a/pkg/compiler/lib/src/ssa/optimize.dart
+++ b/pkg/compiler/lib/src/ssa/optimize.dart
@@ -88,10 +88,6 @@ class SsaOptimizerTask extends CompilerTask {
         new SsaLoadElimination(compiler, closedWorld),
         new SsaRedundantPhiEliminator(),
         new SsaDeadPhiEliminator(),
-        // After GVN and load elimination the same value may be used in code
-        // controlled by a test on the value, so redo 'conversion insertion' to
-        // learn from the refined type.
-        new SsaTypeConversionInserter(closedWorld),
         new SsaTypePropagator(compiler, closedWorld),
         new SsaValueRangeAnalyzer(backend.helpers, closedWorld, this),
         // Previous optimizations may have generated new