Revise assertions and fix bug in the implementation of shifts

runtime/vm/intermediate_language.h

Index: runtime/vm/intermediate_language.h
diff --git a/runtime/vm/intermediate_language.h b/runtime/vm/intermediate_language.h
index afa2f8a41a27023800f4f96e79952ebf3502a6b1..4b2a4eaff1b7d41b1b1ca8d76c84944535ad468b 100644
--- a/runtime/vm/intermediate_language.h
+++ b/runtime/vm/intermediate_language.h
@@ -7244,7 +7244,7 @@ class ShiftMintOpInstr : public BinaryIntegerOpInstr {
   Range* shift_range() const { return shift_range_; }
 
   virtual bool ComputeCanDeoptimize() const {
-    return has_shift_count_check() ||
+    return (!IsShiftCountInRange()) ||
            (can_overflow() && (op_kind() == Token::kSHL));
   }
 
@@ -7262,7 +7262,10 @@ class ShiftMintOpInstr : public BinaryIntegerOpInstr {
 
  private:
   static const intptr_t kMintShiftCountLimit = 63;
-  bool has_shift_count_check() const;
+
+  // Returns true if the shift amount is guranteed to be in
+  // [0..kMintShiftCountLimit] range.
+  bool IsShiftCountInRange() const;
 
   Range* shift_range_;