Add support for invoke-static in optimizing compiler.

Support is limited to calls without parameters and returning
void. For simplicity, we currently follow the Quick ABI.

Change-Id: I54805161141b7eac5959f1cae0dc138dd0b2e8a5
diff --git a/compiler/utils/x86/assembler_x86.cc b/compiler/utils/x86/assembler_x86.cc
index db8956d..3c8a16a 100644
--- a/compiler/utils/x86/assembler_x86.cc
+++ b/compiler/utils/x86/assembler_x86.cc
@@ -54,6 +54,16 @@
 }
 
 
+void X86Assembler::call(const ExternalLabel& label) {
+  AssemblerBuffer::EnsureCapacity ensured(&buffer_);
+  intptr_t call_start = buffer_.GetPosition();
+  EmitUint8(0xE8);
+  EmitInt32(label.address());
+  static const intptr_t kCallExternalLabelSize = 5;
+  DCHECK_EQ((buffer_.GetPosition() - call_start), kCallExternalLabelSize);
+}
+
+
 void X86Assembler::pushl(Register reg) {
   AssemblerBuffer::EnsureCapacity ensured(&buffer_);
   EmitUint8(0x50 + reg);