Get rid of the "spare buffer" cache.

src/arm/assembler-arm.cc

Index: src/arm/assembler-arm.cc
diff --git a/src/arm/assembler-arm.cc b/src/arm/assembler-arm.cc
index 7831ead1d220ae295c8f56c6472ab31dad419aa9..1c690a8a6d720169f44c5e20ceafb4a300f80b7d 100644
--- a/src/arm/assembler-arm.cc
+++ b/src/arm/assembler-arm.cc
@@ -3202,8 +3202,8 @@ void Assembler::GrowBuffer() {
 
   // Compute new buffer size.
   CodeDesc desc;  // the new buffer
-  if (buffer_size_ < 4*KB) {
-    desc.buffer_size = 4*KB;
+  if (buffer_size_ == 0) {
+    desc.buffer_size = kMinimalBufferSize;
   } else if (buffer_size_ < 1*MB) {
     desc.buffer_size = 2*buffer_size_;
   } else {