Support conversion of clamped double values for pixel arrays in Crankshaft.

src/assembler.cc

Index: src/assembler.cc
diff --git a/src/assembler.cc b/src/assembler.cc
index a75c94aa0d4570975be1367588806bad5043bf0d..3c7fc1c6313557b17494907794151eccce614f35 100644
--- a/src/assembler.cc
+++ b/src/assembler.cc
@@ -69,6 +69,8 @@ namespace internal {
 const double DoubleConstant::min_int = kMinInt;
 const double DoubleConstant::one_half = 0.5;
 const double DoubleConstant::minus_zero = -0.0;
+const double DoubleConstant::uint8_max_value = 255;
+const double DoubleConstant::zero = 0.0;
 const double DoubleConstant::nan = OS::nan_value();
 const double DoubleConstant::negative_infinity = -V8_INFINITY;
 const char* RelocInfo::kFillerCommentString = "DEOPTIMIZATION PADDING";
@@ -901,6 +903,18 @@ ExternalReference ExternalReference::address_of_minus_zero() {
 }
 
 
+ExternalReference ExternalReference::address_of_zero() {
+  return ExternalReference(reinterpret_cast<void*>(
+      const_cast<double*>(&DoubleConstant::zero)));
+}
+
+
+ExternalReference ExternalReference::address_of_uint8_max_value() {
+  return ExternalReference(reinterpret_cast<void*>(
+      const_cast<double*>(&DoubleConstant::uint8_max_value)));
+}
+
+
 ExternalReference ExternalReference::address_of_negative_infinity() {
   return ExternalReference(reinterpret_cast<void*>(
       const_cast<double*>(&DoubleConstant::negative_infinity)));