Fix Environment size mismatch in r6849.

src/hydrogen.cc

Index: src/hydrogen.cc
diff --git a/src/hydrogen.cc b/src/hydrogen.cc
index 3ece7bd8e69b32691a9d57b6dec4821c6bbe12df..b49f2bd5a2c18394f59dd4c6bf3504f44aba5b33 100644
--- a/src/hydrogen.cc
+++ b/src/hydrogen.cc
@@ -7644,6 +7644,11 @@ HValue* HGraphBuilder::TruncateToNumber(HValue* value, Handle<Type>* expected) {
     }
   }
 
+  // We put temporary values on the stack, which don't correspond to anything
+  // in baseline code. Since nothing is observable we avoid recording those
+  // pushes with a NoObservableSideEffectsScope.
+  NoObservableSideEffectsScope no_effects(this);
+
   Handle<Type> expected_type = *expected;
 
   // Separate the number type from the rest.