[turbofan] Get rid of truncation by store.

Nowadays, representation inference and simplified lowering can insert the
right truncations based on the use.

Review URL: https://codereview.chromium.org/1512243002

Cr-Commit-Position: refs/heads/master@{#32747}

src/compiler/js-typed-lowering.cc

@@ -1063,15 +1063,6 @@ Reduction JSTypedLowering::ReduceJSStoreProperty(Node* node) {
                                  frame_state_for_to_number, effect, control);
           }
         }
-        // For integer-typed arrays, convert to the integer type.
-        if (access.machine_type().semantic() == MachineSemantic::kInt32 &&
-            !value_type->Is(Type::Signed32())) {
-          value = graph()->NewNode(simplified()->NumberToInt32(), value);
-        } else if (access.machine_type().semantic() ==
-                       MachineSemantic::kUint32 &&
-                   !value_type->Is(Type::Unsigned32())) {
-          value = graph()->NewNode(simplified()->NumberToUint32(), value);
-        }
         // Check if we can avoid the bounds check.
         if (key_type->Min() >= 0 && key_type->Max() < array->length_value()) {
           RelaxControls(node);

test/unittests/compiler/js-typed-lowering-unittest.cc

@@ -782,13 +782,6 @@ TEST_F(JSTypedLoweringTest, JSStorePropertyToExternalTypedArrayWithConversion) {
       Matcher<Node*> value_matcher =
           IsToNumber(value, context, effect, control);
       Matcher<Node*> effect_matcher = value_matcher;
-      if (AccessBuilder::ForTypedArrayElement(type, true)
-              .type->Is(Type::Signed32())) {
-        value_matcher = IsNumberToInt32(value_matcher);
-      } else if (AccessBuilder::ForTypedArrayElement(type, true)
-                     .type->Is(Type::Unsigned32())) {
-        value_matcher = IsNumberToUint32(value_matcher);
-      }
 
       ASSERT_TRUE(r.Changed());
       EXPECT_THAT(