Fix rounding in Uint8ClampedArray setter.

test/mjsunit/regress/regress-2294.js

 // Copyright 2012 the V8 project authors. All rights reserved.
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 // Flags: --allow-natives-syntax
 
-var uint8 = new Uint8Array(1);
+var clampedArray = new Uint8ClampedArray(10);
 
 function test() {
-  uint8[0] = 0x800000aa;
-  assertEquals(0xaa, uint8[0]);
+  clampedArray[0] = 0.499;
+  assertEquals(0, clampedArray[0]);
+  clampedArray[0] = 0.5;
+  assertEquals(0, clampedArray[0]);
+  clampedArray[0] = 0.501;
+  assertEquals(1, clampedArray[0]);
+  clampedArray[0] = 1.499;
+  assertEquals(1, clampedArray[0]);
+  clampedArray[0] = 1.5;
+  assertEquals(2, clampedArray[0]);
+  clampedArray[0] = 1.501;
+  assertEquals(2, clampedArray[0]);
+  clampedArray[0] = 2.5;
+  assertEquals(2, clampedArray[0]);
+  clampedArray[0] = 3.5;
+  assertEquals(4, clampedArray[0]);
+  clampedArray[0] = 252.5;
+  assertEquals(252, clampedArray[0]);
+  clampedArray[0] = 253.5;
+  assertEquals(254, clampedArray[0]);
+  clampedArray[0] = 254.5;
+  assertEquals(254, clampedArray[0]);
+  clampedArray[0] = 256.5;
+  assertEquals(255, clampedArray[0]);
+  clampedArray[0] = -0.5;
+  assertEquals(0, clampedArray[0]);
+  clampedArray[0] = -1.5;
+  assertEquals(0, clampedArray[0]);
+  clampedArray[0] = 1000000000000;
+  assertEquals(255, clampedArray[0]);
+  clampedArray[0] = -1000000000000;
+  assertEquals(0, clampedArray[0]);
 }
 
 test();
 test();
-test();
 %OptimizeFunctionOnNextCall(test);
 test();
-
-var uint32 = new Uint32Array(1);
-
-function test2() {
-  uint32[0] = 0x80123456789abcde;
-  assertEquals(0x789ac000, uint32[0]);
-}
-
-test2();
-test2();
-%OptimizeFunctionOnNextCall(test2);
-test2();