ARM: make sure that the expected code size is computed in predictable scope.

src/assembler.cc

Index: src/assembler.cc
diff --git a/src/assembler.cc b/src/assembler.cc
index 70d35b0f21538b9ad8b589a4af640a733c51d9ff..6b08d34a24bd8dc74c21b52e1240e59898a6ab4b 100644
--- a/src/assembler.cc
+++ b/src/assembler.cc
@@ -158,6 +158,10 @@ AssemblerBase::~AssemblerBase() {
 // -----------------------------------------------------------------------------
 // Implementation of PredictableCodeSizeScope
 
+PredictableCodeSizeScope::PredictableCodeSizeScope(AssemblerBase* assembler)
+    : PredictableCodeSizeScope(assembler, -1) {}
+
+
 PredictableCodeSizeScope::PredictableCodeSizeScope(AssemblerBase* assembler,
                                                    int expected_size)
     : assembler_(assembler),