When canonicalizing branch on StrictCompare ensure that branch gets correct environment.

runtime/vm/intermediate_language.cc

Index: runtime/vm/intermediate_language.cc
diff --git a/runtime/vm/intermediate_language.cc b/runtime/vm/intermediate_language.cc
index 7b8e997150c84ea4da8d6cf68d74312d98a54121..48edba328def479ce21179cdd7aacdf382e20986 100644
--- a/runtime/vm/intermediate_language.cc
+++ b/runtime/vm/intermediate_language.cc
@@ -1821,7 +1821,16 @@ Instruction* BranchInstr::Canonicalize(FlowGraphOptimizer* optimizer) {
     Definition* replacement = comparison()->Canonicalize(optimizer);
     if (replacement == comparison() || replacement == NULL) return this;
     ComparisonInstr* comp = replacement->AsComparison();
-    if (comp == NULL) return this;
+    if ((comp == NULL) || comp->CanDeoptimize()) return this;
+
+    // Check that comparison is not serving as a pending deoptimization target
+    // for conversions.
+    for (intptr_t i = 0; i < comp->InputCount(); i++) {
+      if (comp->RequiredInputRepresentation(i) !=
+          comp->InputAt(i)->definition()->representation()) {
+        return this;
+      }
+    }
 
     // Replace the comparison if the replacement is used at this branch,
     // and has exactly one use.