Revert r16032: it revealed a bug in our bailout environment computation.

sdk/lib/_internal/compiler/implementation/ssa/bailout.dart

Index: sdk/lib/_internal/compiler/implementation/ssa/bailout.dart
===================================================================
--- sdk/lib/_internal/compiler/implementation/ssa/bailout.dart	(revision 16033)
+++ sdk/lib/_internal/compiler/implementation/ssa/bailout.dart	(working copy)
@@ -139,12 +139,6 @@
       if (isNested(userLoopHeader, currentLoopHeader)) return true;
     }
 
-    bool isIndexOperatorOnIndexablePrimitive(instruction, types) {
-      return instruction is HIndex
-          || (instruction is HInvokeDynamicMethod
-              && instruction.isIndexOperatorOnIndexablePrimitive(types));
-    }
-
     // To speed up computations on values loaded from arrays, we
     // insert type guards for builtin array indexing operations in
     // nested loops. Since this can blow up code size quite
@@ -152,8 +146,9 @@
     // inserted for this method. The code size price for an additional
     // type guard is much smaller than the first one that causes the
     // generation of a bailout method.
-    if (hasTypeGuards
-        && isIndexOperatorOnIndexablePrimitive(instruction, types)) {
+    if (instruction is HIndex &&
+        (instruction as HIndex).isBuiltin(types) &&
+        hasTypeGuards) {
       HBasicBlock loopHeader = instruction.block.enclosingLoopHeader;
       if (loopHeader != null && loopHeader.parentLoopHeader != null) {
         return true;