We should never allocate a 0-sized buffer, so never grow from 0.

src/assembler.cc

 // Copyright (c) 1994-2006 Sun Microsystems Inc.
 // All Rights Reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 // - Redistributions of source code must retain the above copyright notice,
 // this list of conditions and the following disclaimer.
 //
@@ skipping 116 matching lines @@
     : isolate_(isolate),
       jit_cookie_(0),
       enabled_cpu_features_(0),
       emit_debug_code_(FLAG_debug_code),
       predictable_code_size_(false),
       // We may use the assembler without an isolate.
       serializer_enabled_(isolate && isolate->serializer_enabled()) {
   if (FLAG_mask_constants_with_cookie && isolate != NULL)  {
     jit_cookie_ = isolate->random_number_generator()->NextInt();
   }
-  if (buffer == NULL) {
-    // Do our own buffer management.
-    buffer = NewArray<byte>(buffer_size);
-    own_buffer_ = true;
-  } else {
-    // Use externally provided buffer instead.
-    DCHECK(buffer_size > 0);
-    own_buffer_ = false;
-  }
+  own_buffer_ = buffer == NULL;
+  if (buffer_size == 0) buffer_size = kMinimalBufferSize;
+  DCHECK(buffer_size > 0);
+  if (own_buffer_) buffer = NewArray<byte>(buffer_size);
   buffer_ = static_cast<byte*>(buffer);
   buffer_size_ = buffer_size;
 
   pc_ = buffer_;
 }
 
 
 AssemblerBase::~AssemblerBase() {
   if (own_buffer_) DeleteArray(buffer_);
 }
@@ skipping 1445 matching lines @@
       r2 = r2 - ad;
     }
     delta = ad - r2;
   } while (q1 < delta || (q1 == delta && r1 == 0));
   int32_t mul = static_cast<int32_t>(q2 + 1);
   multiplier_ = (d < 0) ? -mul : mul;
   shift_ = p - 32;
 }
 
 } }  // namespace v8::internal