Make FlushICache NOP for Nvidia Denver CPU's.

src/arm64/assembler-arm64.cc

Index: src/arm64/assembler-arm64.cc
diff --git a/src/arm64/assembler-arm64.cc b/src/arm64/assembler-arm64.cc
index 524be154c53bef81a410c3c648f456fc32f85bd3..2a1cf0fe13d931ae6a85eba7c0664dc8ab6eb9c5 100644
--- a/src/arm64/assembler-arm64.cc
+++ b/src/arm64/assembler-arm64.cc
@@ -46,6 +46,16 @@ namespace internal {
 void CpuFeatures::ProbeImpl(bool cross_compile) {
   // AArch64 has no configuration options, no further probing is required.
   supported_ = 0;
+
+  // Only use statically determined features for cross compile (snapshot).
+  if (cross_compile) return;
+
+  // Probe for runtime features
+  base::CPU cpu;
+  if (cpu.implementer() == base::CPU::NVIDIA &&
+      cpu.variant() == base::CPU::NV_VARIANT_DENVER) {
+    supported_ |= 1u << COHERENT_CACHE;
+  }
 }