Avoid loading overflow pages just to satisfy typeof() or length() functions

if the correct result can be computed without the extra page fetches.

FossilOrigin-Name: 0733c98c329bc9942460746e9bbaf4b4c94c1520

diff --cc manifest
index 87409f9e290e66364c2f79a93317aabe2a2dbc68,36e1985ccd37fd52bfbc949200192ce0f56d14ea..de13e6de0f95ed50577b4a3ee15b2d1b2f0216e8
--- 1/manifest
--- 2/manifest
+++ b/manifest
@@@ -1,5 -1,5 +1,5 @@@
- C Increase\sthe\sversion\snumber\sto\s3.7.12
- D 2012-03-25T17:25:38.638
 -C Minor\schanges\sto\sthe\score\sof\sOP_Column\sfor\sperformance\sand\sto\sclarify\sthe\ncritical\spath.
 -D 2012-03-28T16:14:50.602
++C Avoid\sloading\soverflow\spages\sjust\sto\ssatisfy\stypeof()\sor\slength()\sfunctions\nif\sthe\scorrect\sresult\scan\sbe\scomputed\swithout\sthe\sextra\spage\sfetches.
++D 2012-03-28T16:22:03.615
  F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
  F Makefile.in 2f37e468503dbe79d35c9f6dffcf3fae1ae9ec20
  F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@@ -993,7 -993,7 +993,7 @@@ F tool/tostr.awk e75472c2f98dd76e06b8c9
  F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f
  F tool/warnings-clang.sh 9f406d66e750e8ac031c63a9ef3248aaa347ef2a
  F tool/warnings.sh fbc018d67fd7395f440c28f33ef0f94420226381
- P 30b8dd326d28c0c08543989e376011ea41773a7e
- R 9c26fe2aaab0d138abb3ef6a21a226f0
 -P ca093103437f141caa3eb11539c6eb7b4dd65175
++P d95f9fb713c7ba4e570556d835fbd77e574afdea 868394761e41b7483a5874426ee052dfb3a9e2be
+ R 14c36b139bb9a241f9fc5fc1fa96e28f
  U drh
- Z 54613266ba9e6cb2a27d5ad8392e74a5
 -Z 95f518d28e036a56a444945b5630fdfa
++Z 15a5058e7b3160b8bbe377cfe96ccfbc

diff --cc manifest.uuid
index 5306c9df0b54310e36be8be55c692338d3299e33,d80571e66d9cfae998f0fc68c4ae3fd440f9b472..60c0fc890f70f67c5ebf913c035e4a5c2d4683ce
--- 1/manifest.uuid
--- 2/manifest.uuid
+++ b/manifest.uuid
@@@ -1,1 -1,1 +1,1 @@@
- d95f9fb713c7ba4e570556d835fbd77e574afdea
 -868394761e41b7483a5874426ee052dfb3a9e2be
++0733c98c329bc9942460746e9bbaf4b4c94c1520