Avoid a call to the runtime system when doing binary fp ops on ARM...

src/codegen-ia32.cc

Index: src/codegen-ia32.cc
===================================================================
--- src/codegen-ia32.cc	(revision 1707)
+++ src/codegen-ia32.cc	(working copy)
@@ -3927,6 +3927,9 @@
 
     } else {
       Literal* literal = node->value()->AsLiteral();
+      bool overwrite_value =
+          (node->value()->AsBinaryOperation() != NULL &&
+           node->value()->AsBinaryOperation()->ResultOverwriteAllowed());
       Variable* right_var = node->value()->AsVariableProxy()->AsVariable();
       // There are two cases where the target is not read in the right hand
       // side, that are easy to test for: the right hand side is a literal,
@@ -3939,7 +3942,9 @@
         target.GetValue(NOT_INSIDE_TYPEOF);
       }
       Load(node->value());
-      GenericBinaryOperation(node->binary_op(), node->type());
+      GenericBinaryOperation(node->binary_op(),
+                             node->type(),
+                             overwrite_value ? OVERWRITE_RIGHT : NO_OVERWRITE);
     }
 
     if (var != NULL &&